What bugs me is we have Sturgeon "strongly advising" people wear masks in shops but the supermarkets I've seen don't have staff wearing them. I would have thought H&S would be all over that.
Supermarkets are not generally places with a strong health and safety culture. Bit of health and safety around yards (not necessarily that stringently enforced) and pallets. Date checking (not as rigorously done as people might think). A few other things. Supermarkets are the sorts of places where even if they were mandated without interventions after 2 weeks only a third of the staff would be wearing them. The most H&S environment is probably deli/counters.
The workers who've been there for Feb/March/April/May working continuously will have a very different idea of the risk to many of the rest of us. Supermarket workers are definitely not sticking to 2 metres from the rest of the staff, which will be one of the types of risks. If a supermarket worker gets it, it is likely to spread to other workers as happens every year with norovirus and ordinary flu. The risk at the moment won't be quite as high as I think people are staying slightly farther apart and the shops are emptier. When I worked in a supermarket/pharmacy I had a different attitude to seasonal flu (not like coronavirus). I was coughed and sneezed on at close proximity, but if I tried to keep my distance and handwash along with a young and healthy immune system I didn't get it. That's not to mean you behave in a silly way, just saying that how the workers will perceive the risk is different from us closeted up at home (including me). Now I go outside extensively for exercise I'm happyish with that, but I'm not going to any indoor environments far more nervous about that than if I was back where I used to work.