Many if not all animal rescue centres in North America require medical/vaccination fees to be paid (as well as spaying and neutering charges) before one is allowed to adopt.

Vet fees are not cheap here - they are not charging you in order to make money, they're charging to cover the costs only. Otherwise, they would not be able to take in as many animals as they do - if you don't want to help these stray animals then that's your choice, but at least inform yourself as to WHY the fee is being charged.

It isn't a gratuitous charge.

Signature line > "You can't fix stupid"