I let my cat wander freely, and unlike what your post is saying, she doesn't kill for fun, she kills and eats her prey, and it's not like common birds around here will go extinct because of her, not that she only hunts birds, she's hunted, killed and eaten mice, rats, gophers, moles, shrews, mostly common rodents, although twice she's killed juvenile squirrels and this morning ate a whole chipmunk the only ones she wont eat are shrews. She actually barely eats her kibble because she just gets her own food most of the time, which if you want to read something about the production of kibble and how much climate change it actually contributes to and henceforth contributing to the destruction of mankind and millions of other species, you can read about the meat it uses here:
As for eating other people's pets, it's not like anyone where I live owns a rodent small enough for her to eat, and if they did, I very much doubt they'd let them out of the house without supervision, and anyone who does this honestly shouldn't own such a pet if they can't be fucked to see if the hamster doesn't crawl through a hole in the backyard fence or gets snatched up by the very birds of prey you mentioned (if they can catch and carry away a cat, they can very well catch and carry away your rabbits).
As for predators, I live in a pretty suburban area, so the most I really have to worry for her is being run over, or being eaten by a coyote (which is rare for a coyote to be in a suburb), there's lots of massive trees here and the sorts of birds of prey that live here always go to big open areas. I've had her for like seven years now and nothing really bad has happened to her outside, once or twice she came back with an infected eye which was easily treated. She's much more likely to be attacked by a possum or a raccoon or even just another person's cat, but she's clearly smart enough to avoid those.
As far as I know, there's no law about keeping your cat out or in, although I generally have a house rule to keep my cat inside at night during the winter so she wont freeze.
I guess though if you're gonna talk and care about environmental damages that pets make on the world, unless said pet is like mine and is a bit more I guess on the ferel side and actually kill to eat, then you may as well just not even have a cat or a dog