[Viliam1234]

I guess the reason is that some kids are so bright that schools would compete for them, most kids are average and the schools would compete for the vouchers, but... there are some kids everyone wants to avoid. For example, that kind that will stab their classmate the moment they get their hands on something sharp (and will find a creative solution even if all objects at school are perfectly soft and spherical). Maybe one percent of population are psychopaths, and they are all kids before they become adults.

In other words, I would love to see a school system based on free association, but what about the kids no one wants to associate with? If you make the system such that one type of school can freely accept or reject students, but the other type must accept everyone, you just increased the density of the problematic kids in the second type of school, which creates a positive feedback loop because now more parents want to take their kids away from there.

Yet another problem is that the density of population is different in different places. In a big city, you can have dozen schools in a walking distance, so it is easy to choose. Then you have places where choosing another school would require an hour of travel, so people would be quite angry if their child is rejected. Should we have different rules for different places?

There are many great ideas, but it is difficult to set up the entire system so that none of its parts explodes. And sometimes removing pressure from one place means adding it to another.