Anecdotally, it seems to me that around 70-80% of people on the London Underground are still wearing masks. Which is to say that the "mandate" is a joke (like so many of our restrictions have been) and clearly isn't being enforced.
The percentage of people wearing masks on the tube, where masks are "compulsory", doesn't seem much higher than the percentage of people who are voluntarily wearing masks in other public places which have no mandate, so the fact that most people are still wearing masks on the Tube is probably less because of the mandate and more because of people's general sense of precaution/paranoia. I suspect if the mask mandate were lifted then most people would continue to wear masks voluntarily anyway, just as they're still doing at the supermarket.
Not true. There is no national requirement to wear a mask on public transport. London Underground and the Manchester Metro have used mayoral powers to require mask wearing - with variable compliance. Elsewhere its down to individual choice.
> Plus mandatory self-quarantine if you are pinged by the NHS app.
Not true. The app gives a recommendation. Only the NHS test and trace service can legally require you to self isolate. And for that you need to test positive (pcr) and not be fully vaccinated.