And your logic is bass ackwards. The solution is to educate people about how bad letting cats live outdoors is, not pretend that their pet is a feral. All you'll do that way is eventually come home to broken windows once they find out who stole their cat. Tell them how much better (and longer) their cat's life will be if they live indoors vs. outdoors and you're much more likely to actually change something.

The majority of people don't know any better. And if they grew up with cats, it's very likely that that's how they were taught that you care for a cat. It's only been in the past 20 years or so that the consensus on how cats should be kept has shifted from outdoors to indoors. Hell, look at how common declawing cats still is.