Bunny -
I agree that a child should be stable before being allowed behind the wheel but perhaps it can be a motivator, something he can do that your younger son won't be able to for several years. My thought of having them learn as soon as possible is that it gives parents more time to teach them. Once they're 18, they can go out and get a license and we can't control it other than to refuse use of our cars. I'd rather have them learning on my watch. None of my kids has a car of their own. I don't consider it my obligation to buy them one and I don't consider it an appropriate savings goal at their ages, school comes first. I allow oldest boy to use my car (a 1989 Camry, LOL!) for work. The kids can borrow H's van but they have to put the gas in. I pay for insurance, etc. but all cars are in our names. The kids check the oil and other fluids, the tires, etc. IF daughter decides to teach upstate or out of state, we will help her buy a car IF she doesn't have access to public transit but she'll be on the hook for insurance, etc.
I think that my point of view is shaped by the fact that my mom never learned to drive and neither have my sister or sister in law and they have all been hampered in life by not being able to drive. My mom was always reliant on my dad to take her places. My sister and sister in law are miserable unless they live near public transit. Also, I want my kids to be able to drive in an emergency or to be a designated driver. Once, when oldest boy was 16 and on his permit, H became very ill. I was at work so my son drove H to the hospital. If he hadn't been able to drive, H could have died because he wouldn't have let the kids call the ambulance. He was in the hospital for 2 weeks.