We even have Vet offices who have kitties in cages in the waiting room. My son and his wife got 2 from their Vet. Usually the kitties are from clients.
Sounds like a great vet! Glad your son and wife found kitties to love who were in need of it.
There are people out there who would rather, or just as soon, adopt from an individual as a shelter and give the pets good homes. I was always able to find good homes for strays when I couldn’t take them in myself.
Nowadays, some of the rescues charge really high fees, even for senior pets, and erect a lot of hurdles (long intrusive questionnaires , letter of recommendation from vet, home inspection — often all three). Even the best prospective pet owner might balk at all that, and those who live some distance away cannot adopt from them because of the home inspection requirement , as the rescue’s inspectors will only consider travelling inside a very small area.