I am going to answer this from how I have seen things turn among my friendship groups. This is largely from social media, but some of it in convos and such too. I make no comment on the things that seemed to change minds, nor the positions some moved to, I am simply posting how I saw it happen. I feel I have to pre-empt with that, as a lot of the views will cause those skim reading to maybe think thats my thoughts or something.
Did they comply in March and April because they had to (i.e. it was actually policed) or did they comply because they were weary of catching the virus?
I think its more, more people were totally terrified on the whole, given the news was constantly focussing on doom and gloom at that stage, making out it was hugely dangerous to even step foot out of the door. As we have learnt more, obviously the illness is not safe in any sense, but its really not the second coming of the plague that it was looking to be for a little, then made out to be for longer by the media.
Among my friends to start with, it was probably a 90/10 split, those who were in favour of lockdown and those who weren't. Despite this, from the limited parts I could see it seemed there was almost 100% compliance with the 'rules'. Many were going over and above the rules and literally confining themselves to their homes and not leaving at all, for anything. This was the case for maybe 2 months. Those not leaving the house at all were always small, but there were many many very nervous. I kew 3 people in total who broke the lockdown from an early stage. All 3 were over 60. And the reason was largely that they didnt want to be isolated (which I understand) rather than just disagreed.
At around the 2 month stage, those on my list who have their own businesses, many just starting out, meaning had only just put all their money into opening somewhere after working for someone else since school and only just getting the money/courage to open on their own (my 'circle' is largely 30-40s due to my own age) started worrying online about their own livelihoods, and questioning if them basically losing their whole life was worth it, when whilst figures look bad when taken alone, when compared to other stuff, is it really that bad? They got pushback at first, cries about how selfish they were for thinking of their own situation when 'people are dying!' and such. This pushback significantly lessened over the next week or so, and more started seeing their point of view and seemed to soften a little.
At the same time, a minority seemed to get even more scared, for seemingly no reason, or no reason I could tell anyway. It was weird, seemed to come from nowhere specific, just a random small explosion on people who are massively low risk thinking again, that they would die the second they stepped out the door. Which in turn, seemed to either 'turn' more people towards 'for most its not serious, chill out a bit' which turned those few people even worse! Accusations of 'murderers' were rife with those people, they commented on normal statuses saying the weekly shop had been done with ridiculous comments. Which again, in turn appeared to either 'turn' more a little, or bring out people who had been quiet for a while. I would estimate at this stage it had shifted a bit to maybe 70/30. I should maybe say here that not all of those with their own businesses that had had to close were against it. A few were still saying 'its worth it for the good of the country' and such. Despite a obvious shift though, only a couple actually broke the lockdown that I know of, ontop of the 3 I knew that did it pretty much from the start.
Anyway, the over the top terrified reaction from the minority eventually got to the point where it became knowledge that one woman I know (fit, very young, gym type) had her family extremely concerned as it turned out she had no shopping in after runing out, she had been in since lockdown and not left at all, was unwilling to order any (as covid might be on it), was unwilling to allow anyone to bring it to her (because you might put covid on it, or it might be there already and washing it means bringing it into the house first), was not answering the door and her phone seemed to be not working, but she totally shut herself off from everything. Was only commnicating on FB, and sporadically too which concerned her family and others even more. She was getting more and more irrational, she had apparently at oe stage been picking up post with bbq tongs and burning it instead of touching it (but she also felt unsafe with it in her house at all) and had ended up taping up her letterbox completely. These concerning things came out over about a week, many on my list all know each other, and at that stage this seemed to set a few off checking, and there were a few 'you are massively low risk pet, this is largely dangerous to the elderly and very ill' type comments which got huge pushback by people putting stories of individual younger people who had died, and so on. The original commenters buckled sometimes to 'be nice' (although personally, I do question what is 'nice' about allowing a young woman to believe she is so at risk she is not currently eating and thought it rational to set fire to her mail), but a couple stood firm on that stats did not say she was at risk and the odd story about someone does not prove she is at risk either. And so on. Given the commenting, yes unfortunately much of this was a very public spectacle. I don't think it should have been, but her family members had no way to speak to her, she was ignoring private messages, so a lot played out on FB as it were. Thankfully, this woman has since had help, shes both let her family help her and has been speaking to a professional (privately, NHS care apparently was not available according to one update) and as I understand it, the help is ongoing, both for severe anxiety and depression. It is no longer playing out on facebook in realtime.
This one girls case appeared to set off a bit of a chain reaction among friends. While I didn't participate in discussions about her/her situation and how on earth it had got to that stage (in honesty, largely as I was not posting at all as my opinions were all over the place and I didn't want to anger one side or the other!), a lot did. Over the course of maybe a week, this switched a huge amount into 'ok lockdowns gone on enough and the media should stop scaremongering!'. It became 'acceptable' to sympathise with those who were potentially looking at closed businesses forever, those who had already lost jobs, those on furlough who knew they were going to lose theirs most likely, and many started getting quite vocally anti lockdown. It was at about this stage too that people started to realise we had been told it was about flattening the curve, but this had been done a while back, why still so harsh? 60/40 ish, still in favour. Amount flouting the rules seemed the same though, there was no noticible increase there, just in anti lockdown sentiment.
The emergence of a lot of people who were saying 'enough', seemed to make those still supporting lockdown go into a slight frenzy. However, unfortunately the arguments tended to be along the lines of 'it was to flatten the curve, but people are still catching it' which did not really go down very well at all. I do wonder if the choice for so many to instantly switch to 'but deaths are happening, we need none!' (when there were many other arguments that made sese that would have gone over much better, most knew eradication was not realistic at that stage at all) was a factor in how quickly more seemed to switch at around that time. Much bickering. 50/50. A few more breaking the rules too..
It stayed at about 50/50 levels until lockdown eased. And for quite a while afterwards actually.
It wasn't until more restrictions were on the horizon before I noticed seemingly large changes in attitudes since then.
One marked difference in those I know came maybe 2 months or so ago. When a lot of people who previously supported lockdown, some extremely enthusiastically, seemed to realise (no particular trigger that I noticed) a very obvious shift away from reporting 'deaths' to instead reporting 'cases', and publically wondered about this. I know I saw a LOT of facebook posts along the lines of 'so once death rates are too low to scare anyone, they switch to infection numbers? But if infection rates are so high, where are the many deaths that we were told would come with such rates?' and stuff like that. Swiftly followed by a few picking up on how longcovid seemed to suddenly be picked up on, again when death/serious illness rates were extremely down. While of course its possible (and IMO likely) that 'longcovid' was just picked up on/spoken about more at that stage, this seemed to switch another few to an almost conspiracy like 'so longcovid comes out of nowhere now that deaths are nonexistent despite high numbers, and the majority find out that this is not as high risk as we were told for anyone under 80?! How convenient' - So yes, a lot seemed to switch about this point, and (again among those I know, not necessarily universal) for most of these it seemed to be reading beyond the headlines and looking into things slightly more themselves. Some were sharing various articles by that 'other group of scientists' who disagree with lockdown too. The sharing of this seemed to take off quickly. One of such articles I recall hitting 40 shares in an hour, which is massive numbers for those I know!
At the same time as this seemingly sudden change in a lot of peoples opinions, MANY were still on furlough or had already lost jobs and were starting to resign themselves to the fact that their jobs are basically gone for the foreseeable future. Those I know who were able to reopen businesses were not able to actually make enough money to meet costs without dipping into savings if they had them. A few have closed indefinitely as its not feasible for them to run at all. A lot of those I know seem extremely stressed about mortgages taken out recently, when they could afford them, but now really cannot, ontop of general job losses. I do not think this helped one bit, and did seem to drive many towards a bit more of a 'I will care about me, I have done enough for others' type attitude, understandably, losing ones job/house would have a bit of a knock on effect on a lot of things, including how much you were 'personally willing to lose for the so called greater good before it gets a bit much'. A few, again, at this stage were flouting various restrictions.
And thats how we ended up at todays position. A story of my friends and their slow change from 90/10 in favour of lockdown, to something like 20% in favour of lockdown.
Its important to note at this stage that the above, is my perception on how people I know have reacted over time, and why they seem to have switched so much. I do say though, that while it seemed about 50/50 by nearing the end, most were still following the lockdown. It was just a lot of moaning at that stage. As more and more restrictions piled on, a few more broke some of the rules. Even the though, it was a small minority.
In our area, we were then put onto 'local restrictions' which included you cannot mix at all outside your own hosehold, regardless of number of people involved. This undoubtedly opened the floodgates to a HUGE degree and I suspect Boris and his 'do this dont do this' messages over time did not help either. But this was for sure the moment the dam broke here.
People were largely following when it was about smaller gatherings, meet in your garden but not inside, and so on. The main resistance was definitely when we were told to not mix households at all, regardless of group size, even 2 people from different households are currently not allowed to meet. And told this would likely be the case until after xmas. Thats when people 'turned off in droves' among my contacts. A LOT are following the other rules, no issues with masks, distancing etc, staying away from public places unless necessary and so on. Would have been ok with rule of 6 too. Its the not seeing anyone outside your household that 'did it' here it seems. And thats the one rule thats being broken constantly. By near everyone I know. Rightly, in my opinion. Thats the one I find shitty, unsustainable and quite lacking in evidence too. The one I find counterproductive but affects me not one bit as I don't go, is the pub curfew at 10pm. I believe a few officials have said the same thing. Many now comment on how previously empty buses around the new closing time are packed and such. Where 11 closing, and 11.20 out, those who couldn't walk home got taxis, was too late to cram on buses.