You have the potential to kill somebody else while driving at a young age
People also have the potential to get Violent and kill someone because you're drunk and have lost your inhibitions as well as a bunch of other stuff.
I don't agree with the driving age being 15 rather I'd go with 17 (Prepared for college etc that way) and have all 15 - 17 year olds do lessons in road safety.
Anybody has the potential to kill while driving but I believe better education on the matter will drop fatalities in all age ranges.
Back on topic: I was never dared to do anything like that as a teen but then I was quite popular with the ladies for a nerd. Shame my good looks dropped as I hit my 20s xD! But back then (Jeez I feel old now) the world was a little more relaxed when it came to this sort of stuff... Or at least from what I remember of my teen years.