>you have a point there - but still - I believe (philosophically - probably not legally 'cause I don't know how you would test for it) that a person must have been out in the real world - working - paying taxes - etc. before they are qualified to make decisions for society as a whole.

Main problem there is:
1. There are 30 somethings, some friends of mine for example, who are just now finishing their postdocs. They haven't "really" worked in the "real world" yet. Are they qualified?

2. Child actors. They can make more money before 18 than most of us will see in our lifetime, and pay higher taxes as a consequence. Are they qualified?

As always, it's a balance. We have to draw the line somewhere. 18 came about primarily because of Vietnam. As it also marks the age of becoming a "major," it seems to make sense but there will always be those on either side of the line that make the line placement look foolish.

Personally, I think the nation would be better off forcing parental qualification!