The problem here may be cultural but the biggest part of it is just ignorance apparently some people choose to remain ignorant no matter what
That's what happen when you choose not to try anything new, not to question anything and simply regurgitate the same thing over and over again because you read it somewhere.
Do you know how your feeders are euthanized anyway? I bet not, you probably couldn't stomach doing it yourself anyway, well let me tell you when done in massive numbers like that it's not as fast as you think and if not done properly (again there is a right way to do it) it can be highly stressful and painful too, when the snakes dispatch the prey it's fast and painless.
BTW I am not from the US I am from Europe just like you, the difference I base my recommendations on EXPERIENCE and I believe in EDUCATING not scaring, I also don't believe being better than someone because of the prey I chose to feed.
Anyway you can lead a horse to the water......