> If you are out walking your cat, and the cat bites someone, you should be responsible for that... I suspect the ruling distinguishes between pets that are out in public, vs generally private.

The distinction is in the responsibility it's reasonable for the cat owner to take vs the dog owner. Cats are free spirits, if your cat decides to pop out the cat flap for a fight there's really not much you can do about that. The law isn't even 100% on what to do when your cat decides to go and live in another house down the road. Are those homeowners involuntary bailees or thieves?

It turns out applying laws for a controlled animal (dogs) doesn't work, so the best we can do is try for half-way between a pet and property. My expectation is that AI is similar and there is no "aha, it's so easy, just do as we do for foo" as is proposed.