Well, they do have some leeway to dictate who they will serve, right, like no shoes, no shirt, etc. And you can use a cotton cloth, or paper towel. Mind you some people have challenges using masks, heart or respiratory problems, but you can use pickup or delivery for food.
Only seen signs suggesting it here. Did get a laugh out of some dude refusing to wear one as doing so would not be manly at Whole foods of all places.
Masks are great, helps to cover my ugliness