I read that euthanized dogs account for 52% in cause of death in dogs. That means that if vets don’t offer a low price, most people will just kill their dogs and the vets won’t get any business anyway. If the surgery isn’t profitable, they will tell you that euthanasia is the best option.
I don't know how that may be skewed (incl. shelters, pounds?). I would say that the surgery I described was pretty major, and other than a volume discount (we have horses too), I didn't complain about the price.
Same for same,assuming the vet made a reasonable profit, the cost of the same in human terms would be astronomical.