I'm going to try drawing parallels with a historical event of large scale that affected children. And a somewhat clunky analogy.
The mass evacuation programme in WWII. Whilst it was undoubtedly a good idea for many, some suffered as a result - HOWEVER, what it did achieve was to show people the sheer scale of deprivation, neglect, malnutrition and vulnerability that thousands of those evacuees had experienced prior to being moved.
It hadn't been a secret as such, but there had been no real measure of it, no real will to do anything about it and for those who were living outside major cities, there was a real will to want to address those problems once they could see them with their own eyes.
As a result, although I don't think that anybody would ever claim that War is a good thing, the fact that it happened and evacuations were necessary enabled new information, new discussions, a will to do something as it couldn't be ignored and, combined with the advantages of rationing ensuring that by the end of the 1940s, children were on the whole healthier than their peers a decade earlier.
Actually looking for and finding a problem is not the same as causing it. If I find the fridge is leaking, it's not my fault that it's leaking for noticing that there is water on the floor - and it's not my fault it's leaking for then pulling out the thing from under the counter, possibly tearing a bit of the flooring, sweeping out cobwebs and looking to see there's something in the back of the drip tray that has caused it to overflow and is also soaking into the kickboard of the cupboard next to it so that it is rotting;
- but I have suspected there is an issue, I've investigated, I've caused some disruption and possible unhappiness (with DP now being chased across the room by a rather large spider, so both DP and the spider are both rather wishing I'd left well alone) and as a result of actually looking rather than largely ignoring the small amount of water at the front of the fridge, I've identified the scale of the problem, some unknown additional consequences of that issue having been left and I can then take steps to do something to resolve both that problem and some of the consequences of that leak (needing a new kickboard, for example).
We have been saying for years that there's a puddle of water at the front of the fridge, but it's been ignored because it would be too disruptive, the spiders won't want to be disturbed, nobody likes spiders coming out into the kitchen and we probably won't like what we find if we pull the fridge out and look, as it'll cost more and once we'll know that the actual scale of the problem, it could result in expensive trips and the inconvenience of going to B&Q to try to source replacement kickboards - ignoring the fact that if it continues to be ignored, that water could lead to an electrical shock, slips and injuries and in time, the need to replace the entire floor unit or even the floor with all the expense and disruption that entails.
In this analogy, Covid could be represented by another event - say, the washing machine breaking down. It's necessary to pull that out and have a look behind it in case there's water damage behind it or the water is getting close to a power outlet. That's then led us to look behind the fridge we were told to ignore and find out there was already a long term problem that needed to be brought into the clear light of day so it and its consequences can be dealt with.
Some of the things we'll find aren't actually problems. They might have been, but now we've looked properly, actually, it's OK - there isn't a mouse nest behind there (finding that some children aren't actually missing, they're safely home educated, in the private sector or in other schools). Some are problems but they can be dealt with quickly - sweeping up crumbs down the side where the toaster sits so as not to attract bugs (so they're children who were awaiting a school place and now the local authority has ordered a school to take them immediately). And some of the things will be big problems that have to be dealt with - the children who were abused or neglected or did not receive a suitable school place despite the best efforts of their parents. But in all, nobody knows for sure what's going on until there is a compelling reason to insist that we pull the appliances out and actually look at what's going on behind the shiny white facade.
Covid was the compelling reason. And now there are no more excuses, we've got to look. Now we know they're 'missing', we've got to find the children. We've got to find why and how they've dropped off the radar. Sometimes it will all be fine, sometimes it won't. But that's not all the fault of Covid. It's the fault of the lack of will on the part of government to be looking in the first place.