1) An under 18 person cannot get his/her own insurance without a parent or legal guardian to sign the application, or buy a car.
2) If he lived under MY roof under MY care, and under My legal authority? You bet your arse, whether he pays or not!
The value learned from buying your own car and paying for your own insurance is not freedom in the sense you are talking about. Because he pays for his own car and insurance doesn't give him the right to drive stupidly. It gives him the right to do what he wants with the car aesthetically.
Buying his own car and insurance teaches him responsibility, valuing what he has purchased and hopefully pride in getting something for something.
Now, at age 18, if he works, is off all of my policies, doesn't owe me for cars, pays his own insurance that has high liablity coverage, the GPS comes out. I've done my job.