Another thing that might be a factor is the length of time it takes to get an actual license in some states. Here in MD, new drivers regardless of age,must go through driving school with a learners, then apply for a provisional license after 60 hours broken down by night, highway etc,then after another year trouble free get their permanent license. My son has done the class and seems to be uninterested in getting his permanent license, as he walks or takes Metro everywhere.