Your analogy of driving and smoking doesn't hold up. Tobacco use has known health risks. There are risks to driving a car, true, but they are of an entirely different sort. What it is, it's a matter of being mature enough to make a sensible decision. Sale of alcohol is prohibited to minors, just like the sale of tobacco. The reason for this is that until you reach a certain age, become an adult, you're not likely to make very wise decisions regarding anything. That is also why you are not given a choice as to whether you're going to go to school or not. You go; that decision has been made for you along with a whole lot of other decisions.
I smokerd a good deal more than one pack a day for years and years. I gave it up about 10 mon ths ago. Wisest decision I ever made.