I dunno...the two peet's by me have pretty big bins, and probably have 12-15 of them?
I don't spend a ton of time in there, but I very rarely see anyone buying beans (might have something to do with the demographics of the stores I go to). And the bins are always full...so if they are selling a lot, they are still topping it off, which means there is still a full bin to dump back into the bag at night. Unless they throw away the beans that have been sitting out, you are definitely getting a mixture of beans that have been sitting out a fair amount (especially since some of the roast dates are fairly old).
Seems like it wouldn't be too hard to have a lid on the bins...some clear UV-protected glass would at least keep the air from circulating and provide some protection.