1. Kids today are so overly babied by the "educational system", their parents and society in general, a child's brain is shaped by his/her surroundings and when they're being treated like a small child until age 18 (or in some areas, 21), they're brain shapes into that of a child.
2. The "educational system" (public schooling) fills the kids heads up with a bunch of bullshit academic curriculum which 95% of the kids will never even use in real life.
3. When they're a very young age (1 - 6), the kid's parents, school or some idiot will teach the kid a bunch of fairy tale bullshit (like santa clause, tooth ferry, etc) and it's not uncommon (at least here in America) to see kids believing in that garbage until they're 13.
4. Most parents now days monitor everything they're kid does until he/she is 18, if a kid has a problem with another kid, they're parents always have to get involved.
So, when they're stuck in school from the age of 5 to 18 or 21, are kept away from everything and can't even take care of they're own damn problems, do you really think that's good for they're development?
I've noticed people who work and take care of themselves at a younger age are much smarter than ones that stuck in skill focusing on their bs academic curriculum until 18 or 21.
It would also be better for the economy to lower the age of majority because the government wouldn't have to spend so much money on schools, "child protection services" which seems to mainly focus on keeping kids small children until 18 or 21, and many other things.