my understanding is that hardware stores and garden centres didnt have to close -they did so because they were concerned they couldnt comply with social distancing and minimise risk to staff sufficiently.
It seems to have given them time to sort out social distancing and make it safe for their workforce. Sky had a go at a minister on the brief today saying allowing it for unnecessary work was sending out mixed message. Crowds rushing to B&Q etc. Her ministership replied - no different to supermarkets and working wll. Actually going how it's being done round here I think many would find working there a better option than the till and stacking at supermarkets.
Personally I would be happier if all wore masks when people can be closer to each other, Washable cotton - that seems to be what the Asians wear. What's not a good idea is ones made from man made materials. Even if it only cuts transmission by a couple of % it's still significant. No answer from SAGE so far. I'd guess it's mostly a supply problem. More than one country has introduced them now. We need multi millions quickly and at none rip off prices.