That stuff really isn't necessary in much of the US (many non-urban areas... thought not all). I don't even always lock my car doors in some places. To someone who's not used to it, it's probably amazing how benevolent people and society really can be.
I lived in a town where if someone was running into a store for only a few minutes, they would probably just leave the car unlocked, with the keys in it, and the engine running.
It varies from jurisdiction to jurisdiction. You can indeed be financially liable for leaving your keys in the ignition, if the car is taken and a crime is committed.
You don't have to live in a place like that for it to happen to you.
This is happened to me in the nice parts of town that are close to public transit. They smash a few windows run across the street and jump on the train. . .
Well, that can't happen where there isn't public transportation. Also, where I live, if you're trespassing in people's yards, you might get shot. And yet it's a super-safe place to live. Who would have thought?
