It is really sad... I don't stop and offer anymore help unless I know someone, otherwise I call 911 and let the police handle the situation. It is sad, but being alone I just can't take the chance.
I remember when I used to drive to Boise State University to go to school. I broke down one time on the interstate, and I rode with a trucker to the truckstop. It was pretty safe then, now I would never dream of getting in a semi with a stranger.