[ugh]

I don’t think this has anything to do with the side of the Atlantic you are living on. People grow up in different surroundings. Leaving your car unlocked, with keys and valuable stuff, is obviously no problem at all if you are from a really small village where everyone knows everyone. If you grew up in a larger city where no one knows no one the thought alone of leaving a car unlocked would probably make you uneasy.

I’m from and grew up in a small German town (pop. 40,000) and I can pinpoint pretty exactly when I start feeling uneasy. I’m ok with leaving a car unlocked for a few minutes (not much more than five) but I would not consciously leave the keys (even if I only stop the car in front of my home to run in and get something) and I would always make sure that no valuable stuff is visible.

That’s the level of precautions I’m personally comfortable with but I know other people with different comfort levels.

(Of course there are always situations in life when you just do something stupid for no good reason at all except that it seemed like a good idea or comfortable at the time. The likelihood of being the victim of a crime even if you leave your keys is quite low, so sometimes you might just want to be lazy.)