It’s a…weakness in schools drawing from a geographic area.

A school is not just the facilities and the teachers. It’s also the student body, and going to school with kids who care about education is better for education outcomes than a school with people who don’t.

This is why private/selective schools get such outsized results, they pick and choose the “best” students and let the wealthy leach buy their way in.

The effect is that the public schools don’t have this “cream” or the money.

If you want good outcomes. You functionally need to outlaw private schools.