The same reason you can’t opt out of paying for roads on streets you don’t use. The obvious and immediate result would be that poor communities would have shittier roads than wealthy ones, beyond the point of which that is already the case.
The real difference is the level of parental engagement and support.
School districts want to retain good students & parents for the exact same reasons those people want to leave.
Rich students are dragged down poor students & parents, but poor students are dragged up good students and parents.
There is clearly a winner and loser to the arrangement, but it isn't because the school gets less tax revenue per student.
Tax revenue would get redistributed on a per car basis.
The real difference is the level of driver engagement and support, of which roads get maintenance.
Road districts want to retain good vehicles & drivers for the same reasons those people want to leave.
Rich drivers are dragged down by poor drivers, but poor drivers are dragged up by good drivers.
There is clearly a winner and loser to the arrangement, but it isn't because the road gets less tax revenue per car.
It would be more accurate if some citizens were doing additional road repair and cleaning outside of the government, and other citizens were digging potholes in their free time.