We have a catio for our cat.

We used to have outdoor cats when I was a kid (not my choice and my mom didn't know better at the time, she is more environmentally aware now). We had 1 get hit by a car, 1 poisoned, and 1 beaten to death by some psycho (vet said the trauma was indicative of blunt force but not what would be expected if a car hit him) all in a period of two weeks and after years without incident.

Even if you don't care about the environment please keep your cats inside for their own sake.

Also, in many towns if your cat (or dog) has killed native wildlife the town is allowed to seize your pet and euthanize it or rehome it in addition to fining you. Just as you are held legally responsible for your pet attacking a person you can also be held legally responsible when they attack a non-pet animal. As an example robins are protected under the Migratory Bird Protection Act, killing robins can apparently result in a fine of up to $15,000 and up to 2 years in prison. I doubt a judge would throw the book at you for your cat killing a robin, but they'd be well within their rights to fine you $500; as an acquaintance of mine discovered when his cat killed a robin at his neighbor's bird feeder and the neighbor caught it on camera and reported it. The cat was not euthanized, but they were told any future reports would result in the cat being seized and then either killed or rehomed depending on a behavioral evaluation.