I used to get harassed by a nature lover up the street about having cats outside.
I have mice, gophers, etc..need cats to keep them down, especially with feed we have for critters. Now, he hates how they kill little birds, lizards and snakes. Granted, cats eats a lizard, it makes them so sick it about kills them. Oh, and squirrels. Cats are hard on squirrels. (You should have seen how the squirrels were hard on our fowl. Killed chickens and ducks).
Anyway, we had this conversation, not too long ago. Then I enlightened him how well fed our hawks, coyote and other higher on the chain carnivores are. We lose at least 50 percent of our cats every year. Mostly to local predators.
Now granted, one can argue that we live in the wild, so we are the ones invading etc. But, a one size fits all attitude about anything is a fallacy. Having livestock in rural areas lends to pests, do we do away with the livestock, or things to catch the pests. Will there be some cracked eggs in any solution.
Urban areas are different. Different circumstances.
I can see where cats introduced in places can cause problems. But there is really no perfect solution everywhere with any thing.
Not long ago, our little indoor tuxedo cat got out side and was run over by a speeding motorist. Broke my heart. He died chasing quail after his escape. SUCKED! Little devil bolted out the door as it was cracked open and we could not catch him. Most our cats are barn cats that come in and out regular. Especially come winter if it is real nasty out. To what solution. Oh well. I'll just refrain from making a one size fits all statement to my fellows and try to expound ideals with a broader brush stroke.
Just.my .02
Oh, and just a note on the dude up the street, I am pretty sure he was the one that got in our back yard and let a dog we had on a run with animal controls permission. Dog was a livestock killer and the choice was put him on a run or have him put down. Couldn't keep him in the house, he killed cats and tore stuff up. Never could get him potty trained completely either. Rescue pup when we got him. Not cool at all doing something like that.