Dear WayneS,
Your academic question, placed in the light of the present national job market, is moot.
The only way that teenagers can earn enough for an automobile, these days, and the funds for the insurance rates, and the maintenance thereof, is with mommy and daddy co-signing a loan, which there has always been a 50/50 possibility of getting stuck with, or the legal fees for Johnny/Jane’s one time idiocy.
I had a part time job after school, was in athletics, earned an ‘A’ in economics, bookkeeping, and two years’ worth of the Russian language, lived in a city, and either rode the city bus to school, or my bicycle.
Good for you. But does that make you qualified to tell other people how to live their lives? YOU didn't need a car, so why would ANYONE need one?
I live in a rural area with no bus service and dangerous roads for riding bicycles. The nearest store (and it's a little one) is about 7 miles away. There are plenty of small farms and businesses that need assistance so work is there for young people if they want to work.
Also, I wasn't talking about a new car, or even one of particularly recent vintage (so your reference to co-signing a loan is "academic" and "moot"). In my opinion, nothing builds character for a teenager like having to diagnose and repair his (or her) old junk-heap vehicle so he can travel where he needs or want to go. And nothing motivates him (or her) to work harder so he can afford a nicer vehicle, either.
I got my first job on a farm at the age of 13. I bought my first "junker" vehicle at 14, and promptly sold it for a profit without ever even driving it. I bought my second vehicle at 15 years of age. With many hours of assistance from Dad, but very little of his money, we fixed it up so that it was ready for me when I got my driver's license at 16. I worked very hard to pay for maintenance, gas and insurance.
I will not deny my son that same type of adventure if he chooses to go that route.
Everyone has different life experiences, and one size does NOT fit all.