I’m new to this forum, so I know the tread is old. I just got to make a comment on the topic anyways.
Where I live in a small Norwegian island, they all park their cars with the key in the ignition, or at least to be found inside the car.
So I’ve done this sometimes. Just because it’s easy, specially during the winter time.
In a populated area it would have been more difficult, but nothing is impossible. If you get a ride, and the driver just leaves the car for a minute. That’s enough. I did that when I still lived in a city.