Thants not an accurate description of how vouchers work. Tax revenue still gets redistributed and split on a per student basis just like it would otherwise.

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.