You’re absolutely right - it is basically unprecedented in history, much before the last century or so, that we would throw children together by the hundreds in a situation where they can’t possibly be effectively supervised all the time by the adults, who they outnumber by a factor of about 10 to 1. I’m not sure though, in the modern age, that expecting every family to home school their children is realistic.
One thing schools could do is take complaints of bullying seriously, and make the bullies suffer for it, not the bullied. Suspend/expel them, and make the parents of the bullying deal with the fallout of that, like finding another place for their kids to go to school. Somehow it always seems to be the bullied who have to accommodate the bullies.
We should return to Little House on the Prairie, a piece of chalk and a slate. At least then all kids could read and write.