I think the problem for a lot of us is that our only option is a pet chain store because of where we live and whether or not we can buy online. So, it's either that, or nothing.
Additionally, it seems to depend upon the store itself and its management/employees. For instance, our Petsmart takes good care of its bettas and has an employee there who knows how to take care of them. Our Petco just makes me want to cry when I've gone in. I refuse to purchase anything from our Petco. But I'm sure there is someone who will tell you that their Petco does a good job with their bettas and vice versa with Petsmart.
I do think that if the option exists, then one should not patronize a store that treats its animals as lifeless objects.