But that would require testing of every single person using someone’s subjective standards.
No, it wouldn’t.
It is a legal issue.
Our lawmakers can analyze their own experience, and scientific evidence of maturity, which they have.
The consensus is 18. There are variables. Besides retardation, some are very mature at 16 and some aren’t until they are 20. 18 is about right.
If you have no legal age of majority, then, every time there is a crime, or a responsibility, you have to subject the accused or the responsible for various maturity traits. EVERY TIME.
instead, we say, if you are 18, you are an adult. You have adult responsibilities and are answerable for your behavior as an adult.
Shall a man have to provide for his son until he is 22, or be charged with “child” neglect, because his son is immature? Shall a twelve year old be put in an adult prison? Shall a 14 year old be deemed mature enough to consent to sex with a pimp? Shall a 20 year old gang banger be determined a “child” so he’s not responsible for his murderous ways? I hope not.
18 works. I could take an argument for 17, or 19. If the majority of the country wanted it. But 18 works.