You guys must have bad PetCos. Mine is good with bettas, relatively. I have been there but once and found 2 dead fish. They move them in winter so they don't get cold by the doors. Lucky Stars has a great recovery. I'm working on my first rescue Dominic. Some places are awful. Mine takes good care of their fish as far as pet stores go. No 10 gal per fish but not the worst I have seen by far.
I can't see the picture but it sounds horrible enough by the description. I can't help but feel the common idea you see on this forum of saving the fish is a good idea. It seems to be a common thing and you are giving them the sale, which means they will continue to treat fish terribly. If you want the abuse to stop you are better off not buying and trying to convince others the same. For every fish you save you encourage another, or maybe even more, to be bred in it's place and sold via the same horrible means.