Something that struck me when I moved to this country was that vet care is very expensive. I dont have a lot of countries to compare to but I know in Sweden and Norway they are rather similar. Both countries way higher taxes than here, about the same income level if you see to similar jobs. Yes the majority of people have insurance for their dogs, but even without a spay or neuter will run you about $100 in a very good clinic with monitors and bloodwork. So in general I think vets here could charge way less than they do.
I am fortunate though, I found a wonderful vet here,they charge about $ 130 for spay of a dog who is approx. 100 lbs. And that is including monitors and blood work.They charge $11 for the rabies vaccinations and are overall very modest in their billing.
So if the vets were more into actively working on getting the overpopulation down I am sure that could be done.
Marit