I understand clearly that you think domestic cats are a natural part of the ecosystem, which they are not. Just because they were introduced a long time ago that doesn't make them natural predators, and just becsuse their impact on native wildlife started a long time ago, that only makes it all the more damaging.

Yes we have wildcats, but like any animal, they have a natural niche. Domestic cats are simply everywhere and their populations are sustained by humans far far above any possible natural population numbers.

Therefore it is completely relevant to keep domestic cats indoors. I don't know about the US approach you're referring to, but I expect that domestic cats can have a similar impact there as anywhere.

There is simply nothing natural about domestic cats in natural ecosystems. I presented four peices of evidence and you still don't see it!

The say the UK lacks predators, you clearly seem to have read one thing about it (I'm guessing about wolves, and therefore large predators, which have a completely different ecological niche to small cats, wild or domestic) and extrapolate that to equate this idea of yours!

You've simply got it wrong.