I think there is some misuntderstanding about private schools. Private schools are not just for the wealthy. There are inner city private schools supported by donations, and private Christian schools, supported by their congregations.
The private Christian school that my daughter and grandsons attended had a few "wealthy" kids but most were middle class. A few would be considered "poor." The church provided scholarships for the poor kids. Most families pay their own tuition by making financial sacrifices. We were one of those families. One of my daughter's schoolmates arrived at school every day in a white limo driven by her body guard. My daughter's car pool arrived every day in our very old, barely-running used car. A few times I actually had to push it part of the way. I opened up the trunk with screw driver, and always carried containers of car fluids and water with me.
My daughter wore yard sale school clothes. We scraped and scrimped to pay for her schooling. Many other families do the same thing.
The kids attending her Christian school were of all academic levels. They weren't the "smartest." Some were physically handicapped.
Why should parents who send their kids to private schools donate money to public schools? We already pay taxes to public schools that we don't even use.