Felons and rights.
You know, the Constitution says that if you're convicted of a felony (thus demonstrating a certain lack of moral fortitude, to say nothing of rational decision-making ability) you lose your right to vote. We've since enacted other laws restricting the rights of a felon to own a firearm. So it seems reasonable that when a man commits a felony and violates the social contract, abrogating his rights, that we move further to restrict his right to operate a vehicle on the public roadway.
Do the crime, do the time. Lose your vote, your gun, your car.
But is the more obvious moral of this story that if you ride a Harley-Davidson, you will be able to neither outrun nor outmaneuver a Dodge minivan?!