There could be so many different spins on stories like this I guess you'd have to just take each case individually. Personally, I don't know anyone who goes out looking for cats to grab off the streets. For me, it is a BAD BAD day when I come across an animal that in my judgement needs help, because I can't live with myself if I turn away, and yet I don't have unlimited time and resources to care for them all. A few things on both sides of this story stuck me as odd.
My cat Bullseye, who passed away in January from SCC, was left behind by some neighbors who moved. They didn't *forget* him. Animal Control picked up their dogs. A couple years later the kids came back to the neighborhood looking for him because they had moved into a place where they could have pets again. DH told them he'd never seen that cat and immediately went and hid Bullseye from view. I would have liked to tell the little girl that her kitty had found a good home and was happy, but it seemed better left as it was.
Several of my cats were altered when I found them. I don't know how much effort a person has to make to find who they belong to. With the exception of the road kittens, I make some effort...check vet clinics, ask around, file a report, post a sign. I don't do all of these every time, but I do something. I have NEVER been so lucky as to locate an owner. So I guess the question is, at what point do you have the right to even decide than an animal is unowned? When they show up daily begging for food? Need medical treatment? To date, I've taken 4 cats off the road who were hit by cars, still alive, and had to decide what to do with them. I hate to use money as a measure, but if you put a few hundred dollars into veterinary care for a cat, would you be real eager to give it back to someone who'd let it run across the road again?
One thing I'm quite certain of, if I actually decided to swipe someone's cat because I thought it was being mistreated or neglected, the LAST thing I would ever do is write a ransom note. Kitty would just disappear, and then live happily every after...somewhere else. Ideally, letting the law handle things is what should be done, but I guess I watch too much Animal Police. How many animal control officers are there for hundreds of square miles and a million people? Way too few. Sometimes I think you just have to do what you believe is right and hope that doesn't make you one of the nut cases that always goes to extremes on either side of an issue.