existentialist
Tired and unemotional
I think the way to do this would be to have a small squad of police who can focus on individual shops, and do a couple of hours' enforcement before moving on. There's just no way that this is going to be dealt with in the absence of meaningful enforcement. And "I'm exempt" needs to be accompanied by some form of documentation.Thing is you can't expect shop staff to enforce this, at best they'll get an "I'm exempt" response at worse a torrent of abuse and possible violence from the more extreme lunatics.
This is an interesting take on the legal issues around all this, though...