I'd contend that with youth I have a better perspective on the folly of your adulthood just as you can perceive the folly of my youth. (I'm 17.)
What makes your later view more correct than my earlier view, on this one?
Accumulated experience generally correlates with more appropriate responses, granted. But inappropriate experiences lead to inappropriate responses. How do you verify that your experiences have led to correct conclusions? They are influenced by the society in which you live. And society (the entity itself, not the collection of people involved) generally prefers the status quo, because of natural selection.
Of course there must be a line. There is a minimum level of development necessary for reasonable integration into a society with a specific set of values and expectations. But humans mature at different rates. Age is not the appropriate unit to be using, here. We need a measurement of an individual's ability to _grow_ from immersion in the adult world. Instead of the SATs, we need CATs... Coping Aptitude Tests. It's not such a big leap for the College Board, either. (Now all that's left is to figure out how to measure maturity. Sweet deal.)