You are making wild assumptions about why and when people let their cats roam and the amount of care cat owners give them. Most cat owners call their cats in and keep them in at night. They are also not like dogs and although some breeds are more amenable to lead training or catios most are not.
We never had cats growing up as we were a dog family. When we decided to get two kittens I was adamant they would be indoor cats and we would lead train them.
My husband who came from a cat family humoured me. We lived in a town centre flat and picked them up the week that Covid became a thing so we had lots of free time to lead train them...we failed.
Once they got the taste of the outdoors that was it. They would howl to go out, try to escape via the windows. We couldn't just let them out as we couldn't get them neutered. But once we did they were perfectly happy outside. Have they got into situations an indoor cat wouldn't, of course. But, we make sure where ever we live limits the risks, no fast roads, industrial sites etc.
A few years ago one of them had a seizure and we decided he'd have to be an indoor cat. Despite us spending obscene amounts of money on enrichment he was so miserable he made himself unwell so we discussed with the vet and he goes out with a tracker that monitors where he is and his vitals.
We are now in a bungalow and for the first time have had to let them out at night as it was too hot to keep the windows closed. It was not the easy thing....after the 4th night in a row of multiple live mice being proudly "gifted" we decided to keep the window closed.
Do our cats sometimes kill small birds, yes. Hedgehogs, no. Squirrels, they get out smarted. My brothers dog will take out, birds, rabbits, squirrels, voles, hedgehogs and anything else when in the garden. He's persistent but not as efficient at killing as the cats which is arguably more traumatic for the animals.
Cats are also much better at pest control meaning no poison, traps or hawks to keep the numbers down.