Someone (a scientist to a committee of MPs... not just Dave down the pub) was saying that LFTs are actually better than PCRs at identifying infectious people (if the aim is to get those off the streets while infectious). We know that PCRs can pick up "dead" virus as a positive some time after someone has stopped being infectious. So it makes sense that all the positive PCRs we see aren't actually "new" (and therefore infectious) cases, but could be residual virus from someone who was actually infectious (maybe asymptomatically) weeks ago but is testing now as a contact, or they've been coughing a bit or feeling a bit ropey.
Also, I really wish they'd stop counting and reporting cases - I don't think it's helping anyone any more. There are enough other ways of tracking spread as mibbe says - the ONS survey in particular, which should be enough to give the people in charge an idea of whether hospitals need to gear up or whatever. Anyone else feeling grotty can stay at home for a bit, take an LFT if they really want to know - but no need to register it or anything.
Test and protect seems to have given up for some time now, and I agree, as it stands, it's a waste of money. Even when I tested positive back in July they were only interested in high risk settings I'd been to - not the multitude of restaurants/ museums/ trains I'd been to in the previous couple of days - and I had to provide numbers/ contact details for anyone I considered to be a contact, ignoring the fact that I wouldn't have this for everyone. And for those I gave, it would surely be sufficient to email or text people with the capability to receive that, rather than phone everyone... Anyone who didn't respond to that (button to say, "yes, I understand" or similar) could be followed up by an actual person, and a helpline offered so people can get in touch if they need advice. It just seems pointless and wasteful the way they do things now, particularly as the contacts identified are so sparse anyway... I confess I didn't own up to some contacts as I didn't want them hounded by phone and forced to isolate, but just emailed them to let them know (and they'd already had covid anyway earlier in the year). Which is hardly the point of the scheme!
Also, I wish someone clever could make the positive LFTs a bit more obvious. So many I've seen pictures of as"positive" and I'm thinking "but there's no line there"! Maybe I'm just spectacularly unobservant, but I can't be the only one who would discount many of the tests as negative when they were actually positive... Maybe that's where the "high false negative" thing is coming from.