This is an interesting thread, and can show how different people from different countries have different veiws about animals.
In the UK, 99% of cats come and go as they please, we have 4 so to be 5 cats and all of them are indoor/outdoor cats, one of them will only go out when put out and one only goes out in the dark, but I would never dream of keeping them in.
If you walked a cat on a lead and harness in the UK you would be laughed at, I have one cat who is nearly 20 and yes he does kill the odd bird, but as someone says cats are natural predators and it is in their nature to kill - not nice I know and if I do see mine do it I shout at them.
But like the responsible pet owner that I am, I also go round the front gardens of my neighbours on a daily basis and clean up after my cats as I do my huskies if they go to the toilet while out walking.
I work as a RSPCA volunteer and I know that they do not recommend keeping any animal solely in the house.
I live in the country with badgers and foxes etc and we have never lost a cat on one of them.
Just my opinion - interesting thread.