I recall many times growing up when I felt like my inalienable fundamental human rights were violated in unjust autocratic ways, mostly at school. There was also the time of being a year older than my partner but the potential of ridiculous arbitrary laws having major consequences.

I feel like the age of 18 as some kind of moral benchmark is ridiculous. I feel like it is just tied to the age of conscription. Basing sexual morality on the age when the state can abduct and murder without recourse is nonsense. Most of us likely exist in a duality where we might cringe at "underage" of any kind, but not think twice when a couple of teens are dating and in a physical consensual relationship that is respectful and private.

So from a distant future culture's perspective, like if Star Trek TNG existed in hard SciFi, and there is no need for our present arbitrary policy enforcement, what should be the basis of adolescent autonomous agency?

1. Maybe it is weening, cultural pressures, and education.

2. Maybe it is full independence and self sufficiency.

For the record, this is my favored idea as it pressures society to enable a balanced financial early life and opportunities. It also adjusts to account for real world maturity levels. IMO, it is either this or number 1 as these are derived from individual human life phases.

3. Maybe you think it should be something else?