It works like this:

You get out to help, you suggest the struggling driver gets in the car to steer.
You push 100 yds down the road, next thing it starts up and clears off.
While your scratching your head wondering what happened, YOUR CAR comes flying past with 2 thieving scumbags in, who were hiding when you stopped.

IF YOU STOP TO HELP, LOCK AND ALARM YOUR CAR..