yes instant death by shooting is preferable, but trapped in a cage for hours on end, no food-no water, is more stressfull then 2 or 3 min in the water barrel. there are places where you cant shoot a gun, there is no place where its leagal to trap and release and that is cruel and stressful as well.
there are people that just cant afford the loss of chickens or a 50 dollar fee to have a nusance animal picked up. those chickens and that 50 bucks may be all that family has for the week. people can say make your coop fort knox, but for the poor its just not a fesiable option. they have little to no money and they are just getting by any way they can. and that just might have to include trapping to protect their food supply and then dispatching the nusance animal.
my greatgrandmother used a water bucket because it was a pain to pick buckshot out of the meat. with a nice tomato sauce everything tastes good over pasta.