The age is usually whatever time range a state decides 'kids' are responsible enough to handle a car.
Getting a license makes more sense. It's passing tests to prove that you know what you're doing and understand how driving a car works. Like knowing what side of the road to drive on and what traffic lights and signs mean. To make sure you can handle yourself enough to not put yourself or others in danger sort of stuff. Like having people spar before you actually send them off into battle.