I dated somebody long ago who did this in her spare time. She did this at her own expense because she loves cats. So that's why she wouldn't kill them. I'd imagine this is common.

Because cat lovers will help if you do TNR, but not if you catch and kill.

People (not me) love their "friendly neighborhood" cats, but most of them recognize that allowing them to breed isn't ideal. Maybe you can convince them to nab them, bring them in, and have them neutered.

100% agree that euthanasia is the effective way to deal with the problem.

But, someone in this thread made the very strong point that people will trap and collect cats for free if you're going to neuter and release them.

Granted TNR hasn't worked at all, but at least it's possible to stay elected while the program exists.