It says it's an urban myth and it's false and all that, but what's to stop someone from trying that?

It's the same principle as something that happened to someone I know.

They'd recently bought a new Audi TT, it was a few weeks old when they parked it up in a multi-storey car park. When they returned to their car about an hour after leaving it, they got in, reversed out of their parking space and heard a scraping noise coming from underneath the car, so they got out, engine still running, to have a look. Someone had tied 2 tin cans to something underneath the car, and just as they spotted it, 2 blokes jumped in the car and sped off...

Same prinicple, and that really happened...