And 16 year olds may be mature enought to drive a car as well. But they must be of majority age to be legally accountable for all their actions. This includes voting, drinking, gambling, purchase of controlled items, etc.
This is the sticky point, "maturity" really means jack shit.
Age verifier Northern Alberta
Democracy is two wolves and a sheep discussing what's for dinner.
Freedom is the wolves limping away while the sheep reloads.
Never confuse freedom with democracy.