Exactly! An 18 year old is old enough to die for their country but not old enough to have a harmless beer. That doesn't make sense. They can vote and smoke cigarettes too. If they can have a say in who is going to run the country, I think they can decide whether or not to have alcohol.
It is extremely unfair to send someone to war when they cannot drink. The drinking age was raised by three years about 50 years ago. Since then most kids start drinking even before the age of 18 if not right at it. A person gets all of there rights at 18 except for the right to walk into a bar and have a cold one.