Stopping one store from selling bettas didn't necessarily save their lives.. the same amount of bettas were bred, they were shipped elsewhere, where most likely were in the same conditions (uncleaned small cups). In reality you probably stopped more from being taken home and cared for then stopped from dying in cups :(
It's idea for them to be in smaller cups to be sold, and more economical and safe for them. It's sad that they don't get cleaned often enough- that's the issue. But also remember, that even if they clean the cups once a day in the morning, by afternoon/evening, the cups will always be dirty with waste and food.. so we can't know when/if they clean them. And in small stores, they may not of had enough employees to spare cleaning out the cups every couple of hours.
I personally don't see why a fish store/pet store shouldn't sell them- they are in it for the money, it's up to us, the consumers, to do our homework and research before getting any pet to know what is the proper way to care for them. So basically, if it was a single mom and pop store.. they just loss some income that may of been needed in this economy moreso then in the recent past.
It's sad to see them in such conditions, but you can also walk through a lot of stores and look at the big tanks and see dirty water, algae all over and dead fish. So sometimes there is no real difference between bettas in cups and the fish in the sell tanks. All we can do is provide the best care we can to the ones we fall for and hope for the best for the others.