I haven't fact checked this, but it sounds very plausible. I suspect a large chunk of the 82% who don't self-isolate simply can't afford to. They don't have the money and job security to self isolate, so they go to work anyway. And another good chunk just follow what plenty of people in power have done (Cummings anyone?) and think if the people in power can get away with it, so can I. Until these two things are addressed/fixed I don't really see this improving. And lockdowns won't have much of an impact on this, quite possibly the contrary.