I find the view that kids are incapable of making decisions a little strange. Yes, at a young age people are more inclined to get talked into something they don't really want to do, but this is often an important lesson in itself. Youth is also a time when the majority of experiences are new, and the age when children are first exposed to drugs (nicotine and alcohol included) is also around the age when they begin to make their own decisions.
Personally, I know that lots of the things I did at 16-18 turned out to be a bad idea. That is kinda the point. If at 16 you skip work/school to socialize you might get fired and lose your beer money, do that at 30 you might get fired and lose your house. I'd say the same applies to kids and their exposure to drugs, learning while there are fewer consequences is the point of youth.
