I would say most abuse I've seen occurs through extreme neglect. If I visit Petco a few weeks after they receive a shipment, I see dead fish sitting in cups still on display, which tells you how much care they receive. The water is dirty and clearly not changed often if ever, and there are lots of fish slowly dying of ammonia poisoning. Then when they get a new shipment, the old sick fish are mysteriously gone and replaced by beautiful new healthy fish, until a few weeks go by and the new fish start getting sick and dying and the cycle repeats.
In the uk I havent seen much
My local Paws for Thought branch is perfect at caring for their betta's, sadly however the same cannot be said for the local pets at home branch, the bettas are kept in .25gal tanks with a single tank cleaner in each, I asked them how often they clean those 8(ish) tanks and they replied once every 2 weeks, I told them I was not surprised every one of their fish was dying, the conditions were poor at best, and that if they could not care for them properly then they should stop ordering them or someone would end up reporting them for animal cruelty! All the fish in those tanks are always ill or close to dead, suffering from fin rot, fungus, parasites-you name it the fish is suffering from it!My only happiness comes from the fact that they only have about 8 betta fish in at a time, so the abuse is not on a horrific scale like some places I've heard of!
Just remember that bettas are in the cups for a reason - their safety. They are also not fed (much, if at all) while in the cups for a reason as well - to help maintain water quality (makes it longer before it fouls up). Unfortunately the trade off is not always the proper temp. But the stores don't tend to dip down too low in temp, as there are many live animals in most of them that need the warmer temp.
Being able to have someone spend a lot of time caring for the betta fish can be pricey, especially for smaller stores. Price of staffing, training and the amount of time it takes to do the cups play a part in whether or not a particular store will have people replace the betta water.
Unfortunately it's part of the betta world, and it won't change. A lot of animals out there are in similar conditions, but we don't always see that because once they get to the store, they are made to look cute - they aren't cramped in the small cages together not being fed properly there, just behind the scenes. Bettas you can just see it, but again, it's the only way to keep them safe as they can't place 1 betta in every tank they have - too many incompatible species for it to be feasible. So we just have to either look away, or if you must, buy one to give one a chance at a home.. and I don't believe you will be keeping the trade going by buying from a Walmart or some such place - the stores get money regardless if the fish dies or is purchased, so if you want the fish, just get it :)
It's sad, the lack of as many water changes needed can be considered neglect, but it's the only way most people get their bettas. The only way to change it is store by store - and even then it's not guaranteed due to staffing.
Sad.. but it's the way things go. Fish die, but many more are healthy and happy in a home.
How do they get paid for the fish if the fish dies?
Count it as product loss - stores get a % of the cost for items that are broken (or dead in this case). They write it off.. unsure of exact process.. it's like insurance for items they buy and if something breaks, they get some money back.