Part of the issue will be for retailers to get their own houses in order first.
When all this started, I was appalled at the way the staff at my local supermarket behaved. No social distancing, no following the one system. If the staff themselves do not adhere to it, it makes it more difficult for them to expect anyone else to. A staff member squeezed past Mr BM whilst he was waiting at the pharmacy and when he objected she responded that she had passed behind him so that was OK!
At hospital reception this morning, the receptionist only had her mask over her mouth. I think she might have heard Mr BM's waspish comment though since she popped it back over her nose.