I think it depends on the cat and the location.
Patches and Princes are indoor/outdoor. Patches will claw her way out. She was born feral. I don't really worry about her. She actually looks both ways before crosisng the street, and she handles other dogs and cats well. To trap Patches indoors, or even in an outdoor cage, would be inhumane. She's 17 and still brings home mice from the school yard across the street. I also don't worry about anyone stealing her since no one else can pick her up.
She also seems to understand where her home is, even though she was feral once. There was one time we thought she ran away; turned out she spent 3 days sleeping in the attic and eating dry food late at night. She also once spent 2 days under the house, and 2 days inside an old car (found her in it before we sold it, thankfully).
Princess, on the other hand, would love to live in a studio apartment. She has to be thrown outdoors, and when she's there she refuses to leave our yard and spends most of the time in the garage. Even the sidewalk is much too scary for her.
Puppy would like to be outdoor, but he's indoor only because of his declaw. While he was still a unhomed kitty, he would wander outside, but he never checks for cars, dogs, or other cats. Even if he wasn't declawed, I wouldn't let him out without supervision; he just gets too distracted. When we get a house, we'll probably set up an outdoor cage for him so that he can't get out and other cats can't get in. For now, he goes outdoors on a leash.