I wouldn't blame pet store employees purely, I mean, they're just trying to make an honest living, put a dollar into their pockets, there's nothing wrong with that. If they're uneducated about the species clearly, then maybe they shouldn't be working that department of the shop, but then again, they may have had previous turtle experience, and thought that it was fine.
Same for managers, they probably have had the shop for quite some time and didn't have the time to research turtles, or are not internet-savy (like many older people I know,

), so they may have thought what works best, based on previous experiences or whatever.
So the best thing to do, like the post above me, is to tell them about the site, or give them a few helpful facts, since chances are, they weren't trying to kill your turtle in the first place,
Only exception is, if they are stubborn and persistent, despite their situation and being informed, they go their own way and do things they way they see fit, then they should be slapped upside the head,
Just my two cents.
Hey hey hey.