Society is nothing like school though. Who has 30 friends all the same age that you spend most of your life with and that you can't change for the next 5-8-11 years?
School is organized the way it is, because we need workers and soldiers. Not because we want kids to behave better or to "grow up". People "grew up" before we had schools.
Schools were made to get people used to working fixed hours and teach them the minimal skills required to operate the mills [1]. It's really time to rethink schools (and work).
[1]Behemoth: A History of the Factory and the Making of the Modern World
School is organized the way it is, because we need workers and soldiers. Not because we want kids to behave better or to "grow up". People "grew up" before we had schools.