What makes an Adult and Adult?

The paper is filled with people attempting to pass bogus new Legislature through Congress.  I have something that I’d like to get passed.  What makes an adult and adult?

When you are 21 you can drink.  When you are 18 you can vote.  When you are 12, you stop paying children fares on airlines, now you are considering an adult.  Granted your parents are the one’s paying the fare.  When you go out for dinner, continental style for breakfast, you are no longer a child at 11 years old but an adult paying customer.  The child vs. adult thing is very inconsistent.  Sometimes you are an adult at 14 and other times at 12.  Why?  Is it because there are no laws prohibiting the random moment that companies think you should pay an adult price vs. a child price?  It doesn’t seem fair. 

I’d like a law so I know exactly what I am getting, for my adult/child, wherever I go.  If you are under 21, you can’t be served liquor.  If you are 18, we can draft you and you can vote but you can’t drink.  Perhaps time would be better spent in congress discussing the merits of adulthood vs. the disintegration of the separtion between church vs. state.