Unfortunately the closest thing to a meritocracy that the
United States provides. (meritocracy = success based on merit)
School was primarily set up to keep kids busy while parents work. The fact that it goes for so long is probably the result of our society going through
industrialization. It also is used to teach children what is expected of them in this society: a.k.a. glorifying the middle class (even though only 30% of us are actually IN the middle class!)
It is the No. 1 thing correlated to a bigger paycheck - the higher you get in it, the bigger your earnings later in life.