Whilst I don't want to suggest that people aren't following the rules - every other time people have suggested it of all sorts has pretty much turned out untrue, people have repeatedly followed the rules.
But, last year there were huge restrictions, which made it pretty irrelevant if you actually had a test or not - this time, isolating is more significant, so that could change. However the availability of LFD's may well mean that even if people are unwilling to formally be locked down, they will still test and avoid the vulnerable.
I'm not convinced given the repeated anecdotes of "everyone tested before" and "everyone caught it" is that indicative of testing being that successful anyway, the growth speed of omicron seems high enough that it negative at lunchtime before you enter the restaurant, to singing impromptu karaoke in the pub at 10pm is enough to turn you into a super-spreader. No actual confirmation of that of course, but so many "everyone tested before christmas and we all still caught it" anecdotes.