The slaves were never freed. This is not an accident or oversight, the point was that slavery was too good for Bantu-Americans, America wanted it to be worse for them, and the Bantu just sat there and took it. Nobody asked if they wanted off the plantations, because they already knew the answer would frequently or even normally be 'no.' That and wrecking stuff to show they can wreck stuff.
Likewise, nobody asked if kids wanted to be in school.
Partly this is trying to outlaw the lower class by outlawing lower-class behaviour.
Raze the slum, right?
Theory: no slum, no slum dwellers.
Reality: personnel is policy. There are still slum dwellers, but now they are homeless instead of having slums to live in.
Mainly, America hates children for being weak, punishes them by sending them to school, and the parents just sit there and take it.
It is not a coincidence that homework is unpaid labour.