I am a passionate animal advocate, Deborah, and yet, I must agree with you here. I see no sense to caging an animal that is going to have issues getting adopted. I see no sense to try to rehab a feral animal that has been on te loose for a long time ad has little chance of a decent life.
I would much rather see efforts being made to provide, as you said, humane euthanasia in some cases. I would rather see the efforts to train people NOT to treat their pets like furniture increasde. I would like to see the punishments for idiots who abandon and mistreat their pets be raised.
We had the terrible misfortune to adopt a lovely little rescue dog who turned out to have severe mental issues. He was really nice looking, but vicious, unpredictable and downright dangerous. We had no choice but euthanasia. hardest choice we ever made. still haven't recovered from it. But I know that it was the right thing to do.
Bottom line - not everyone can be saved.