You used to be able to 'win' goldfish at funfairs in the uk but they banned that 20-30 years ago
Unfortunately, using goldfish and other types of fish to offer as prizes at fairs and carnivals is not illegal in the U.K. Although frowned upon there is nothing stopping people from giving them away as prizes, it's sad and heartbreaking but unfortunately thats the truth of it. As Essjay mentioned earlier, local councils can choose to prohibit this cruelty, though sadly, most don't (from my personal experience).
I'd say about 4-5 years ago, there was a fair in my small town. Prizes ranged from bouncy balls, teddy bears and of course... goldfish. Some attractions didn't even care if you won or lost, they'd hand you a fish just for paying your entry to that stall. Though I remember seeing a metal bin there which was used to house all the ones that had passed away. It was horrible seeing a bin of that size almost full with dead fish, all dying for no reason.
As for this "fish store" in Bangkok, the only thing I can say is that it it sickens me. It's high-time people stopped seeing fish as decoration items, trinkets or objects and started seeing them as what they are.... a living being. Some of us call them pets and treat them to our best abilities, others call them a hobby and try to home many doing their best to replicate their natural habitat, doesn't matter which you are they both understand that they have a life in their hands and they need to give it time energy and most of all care. I fully understand sometimes there just isn't any other practical means of transporting them, but, if you have a store you should at least give them the care they deserve until they find an owner and not stuff them in tiny plastic bags to sit there all day (and who knows possibly all night).
I'm sorry for the little rant, I'm just a softy, I can't bare to see any animal in pain or discomfort.