Ethel, that's such a great idea! I'd love to be able to have a locker to stash stuff in so I could be hands free for shopping.
When I worked in a supermarket we were searched regularly and randomly by the security guard when leaving work, bags, pockets, everything, to make sure that no staff were nicking anything.
We weren't allowed to carry any money on us while on duty either, think that was just the checkout staff though.
it might be they do it to lots of people. A sign would be a good idea though to make people aware that bags can be checked to avoid problems.
I have to say I never mind as I have nothing to hide, just one of those things and a sign on the times I guess.