Cats typically roamed free in Eurasia and Africa, where small wildcats were common millions of years before humans ever showed up. This means large populations of feral/semi-domestic cats aren't as disruptive to the ecosystem: birds and rodents have already evolved specifically in response to predation from small cats. This is not true in Oceania, and only barely true in the Americas: bobcats really aren't the same thing as small cats since they are much more widely dispersed. (Especially feral domestic cats, which mostly kill for fun, and live in big dense colonies.)