I'll admit in the years I've been keeping fish, I've seen a lot more education going on in petstores, at least where I am. There was one pet store that had dead fish everywhere - I'm talking 10 fish in one small tank sucked into the filter, dead, while the others were on their way out. I never bought fish from there, and even when I did they'd usually die fairly quickly. Maybe I'm in the minority that it's gotten slightly better (only slightly) - for example, I see less of the injected glass tetras. They also seem very conscious now of other pet stores and criticize and tell you who to avoid. They still don't know everything with stocking, but to be fair stocking can depend on the personality of the fish and to some extent personal experience from fishkeeper to fishkeeper (if a goldfish needs a 75 or 55, for example). I notice they all generally stock less of the big guys that most people can't keep, as well. EDIT: I don't usually buy from PetSmart or Petco, however. I avoid them because they don't apply to those qualities. I buy from small town/local business type stores.
This is just based off my area and doing this for a while, though.
And some of fishkeeping is influenced by culture (thus, people think it's totally fine to go in and demand a goldfish despite having a 1 gallon tank). We go to carnivals and see goldfish getting handed out in tiny tanks to kids who don't know a thing about temperature or ammonia or nitrates or any of it and then they go home and wonder why the goldfish is dead with a bent spine and all their neon tetras were eaten. If you want to help change cultural perception, write to assemblymen and small-government type leaders asking them to stop carnival goldfish in your area. I did and I got an answer - we will be speaking on the phone.