You seem to be operating under the assumption that experience and
intelligence automatically leads to libertarian beliefs. If only! The
facts may justify libertarianism, but that does not mean everybody
who studies the facts will reach that conclusion. Therefore ideology
remains the best way of sorting those who are likely to make correct
policy decisions from those who are not.
I think that, all things being equal, experience and intelligence, as well as a empirical mindset and an unbiased view of reality, tends to lead to *correct* beliefs. Those will not necessarily be libertarian beliefs, but obviously, since I am a libertarian, I think in general they will be. If they make their decisions on an ideological, not a rational, basis, they might make the wrong decisions when either libertarianism is *not* the correct public policy or, more likely, when they misapply their ideological beliefs in a silly way, because they can't understand the facts outside the prism of their ideology.
An analogous situation is the reason why we teach students how to think scientifically, rather than teaching them the laws of gravity, evolution, quantum physics, etc., as a religion, not a series of beliefs derived from empirical facts. This type of thinking is extremely brittle and likely to fail if reality ever contradicts their religious beliefs.
Most teenagers would at some point like their parents to exercise
less control over them, yes. But that does not mean most teenagers
would, if they had the legal opportunity, necessarily seek legal
emancipation in order to rectify the situation. That would be the
proverbial "nuclear option." This option should exist to keep
potential parental abuse in check, but should be extreme enough that
it would not be lightly invoked.
You still don't get it. The reason why children don't have full adult rights is that most don't yet have the ability to make fully informed decisions. This includes the decision about whether or not they are able to make fully informed decisions. This kind of thinking about "nuclear options" is an adult type of thinking...if most children thought that way, then we wouldn't need to distinguish minors from adults in the first place! This is a perfect example of mistaken ideology replacing any type of reality-based thinking.
I'm not sure what you have in mind when you say a "high burden," but I'm pretty sure I disagree. I think it should essentially be simply a matter of making sure the child understands the consequences of what he/she is doing, and doesn't intend to change his/her mind, i.e. it should not be an instantaneous process. Beyond that, I'm very mistrustful of requiring a child to "prove" some particular level of competence. What level would that be, anyway?
I basically think they should have to prove, in front of a judge, an impartial third party, that they can make decisions as well as an adult can, using the "community standards" definition of that term, which is a standard common in many other legal situations. I mean, honestly Starchild, you cannot possibly believe that an 8-year-old, by signing a piece of paper and waiting a week or two, should be able to emancipate themselves from his parents because he's in some kind of temper tantrum that they wouldn't let him sleep over at Tommy's house last night. If you do think this, I beg of you, please never say so in front of any member of the public. People already think libertarians are crazy enough.
Your phrase "able to make decisions at the same level as an adult" implicitly assumes that adults all make decisions at the same level, when we know that in fact the reality is about as far from that as could be. In practice, when kids have had enough, they run away. What I'm talking about is basically a way to allow them to do this without becoming criminals.
In practice, when kids have "had enough," they call their parents names and pout in their room for a few days (or weeks). Even most kids who run away do so because they want attention. I can guarantee you that if what you seem to be proposing had been available to me when I was 13 years old, I would have taken it, as would almost all of my friends at the time. (I ran with a rebellious crowd.) And it would have been incredibly stupid of me to do so, because, like most 13-year-olds, I was not nearly as wise as I thought I was.