I lived in California for a few years, in the San Francisco area. The maority of cats are perfectly content and happy indoor cats. Several friends had cats which never went outside. Two reasons for this:
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The mild climate means the outside has high densities of ticks and fleas. Let your cat wander and it will come back infested.
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Racoons are common, even in built up areas, and racoons are partial to a tasty cat. Let your cat wander and there's a good chance it won't come back.
The point being that cats, if brought from kittens, happily live as indoors only pets.
New Zealand has recognised that domestic cats are a menance to native wildlife and now plan to erradicate completely feral cats:
https://www.theguardian.com/world/2025/nov/24/new-zealand-to-eradicate-feral-cats-by-2050
There is also discussion about requiring all pet cats to be microchipped and neutered.
A few years ago, I was in Spain, in one of the Natural Parks looking for Wild Cats, which we did see. I asked a ranger about problems with interbreeding with domestic cats. The rule is that within the Natural Park, any domestic cat seen more than 100 metres from habitation can be shot. Residents know this and make sure their pet cats don't stray.
So, certainly Spain and New Zealand fully recognise what a threat domestic cats are to wildlife. Time the UK acted as well.