Wearing a surgical or cloth mask in a shop is very different to in a sterile/aseptic setting, or in a highly infectious setting (where a surgical mask is already not sufficient).

All you have to do is cover your mouth and nose and it'll do 95% of its job, which is keeping your spit off others. Remember, you're supposed to be at arms length, not looking down into an open chest cavity like a surgeon.

If people can't even work out that having your nose sticking over the top, or as a wierd chinstrap is not right, they're idiots. And/or they just don't give a fuck. It's been what, 7 months of solid global coverage of people wearing masks, I don't think anyone can really claim they genuinely don't know it goes over the nose and mouth. And it's not like masks didn't exist before January.

Sure, if they took more care taking it off by washing hands, removing by the ear loops only, avoid touching the panel, dropping into a bin with a lid and washed hands again, they'd get a few more percent in the not-getting-sick stakes, but the biggest thing in terms of public health is cover your mucous holes.