that many fish would need a lake!!!!!!!!!

i wonder how pet shops keep their tanks habitable as they seem to cram loads of fish in, and they dont all sell in a day. you'd think they'd be really toxic with
ammonia etc. especially as many pet shops know nowt about fish!
it really baffles me how some people can keep so many fish in such poor conditions.....and i bet luck would have it....they survive! my fish are in luxury (well, they have plenty of space and water changes a few times a week!!) and mine got ill! typical eh!
talking of fish and pet shop conditions.....i've only seen
betta's in 2 fish stores. in one of the stores they're in shoes box size crate things with no decor and look really fed up (understandably!) then in my favorite fish store (where i'm becoming a regular! - its not a chain store, but just a fish owner that owns and runs it and he hires other people with fish experience...hence a good shop!) guess where they keep the betta......in the huge tank in the middle where the plants for sale live! must have been about 1.5 metres square he or she was in luxury! it was my son who spotted it (its at his eye level). i thought it was just plants in there! good idea though! keeps him on his own, but by no means cramped!! wonder how many customers know he's in there though?! maybe the store want to keep him and not sell him?!
anyway, i'm rambling.....i just got a bit excited when i saw him!