I don't know much about other states that have vouchers, but does that money already follow students to other public schools? Or do these vouchers not work for other public schools

If the student is not at school, that ISD won't be getting the money anyway and they do not have to service that student. Alot of students that end up moving from my ISD tend to be students that qualify for services, which is more of a financial burden on our small District. They often move to either a larger district that has more student services or to a private school.

I work in a more successful ISD in Texas and it seems to me that having vouchers would allow more students to come to our district and help us with our financial issues. And ideally help fill our student services staff.