I'm not sure about other parts of the country, but here in the great State of New York property taxes are used to pay for the local school district's expenses (i.e. my "property tax"). In addition, I'm obliged to pay a Village tax and a Town and County tax. Those taxes are used to pay for expenses of the village and town/county where I live.
I often wondered about property tax myself (i.e. the "school tax"). First of all, school districts aren't governments, secondly, I am obliged to pay them regardless of whether I have children currently enrolled in school or not. If I don't pay them, then I can have my house seized by the authorities.
Considering the sad state of public schools and how, sometimes, the manner in which they teach my kids (which is another strange thing, being divorced, my children go to another school district, but I don't pay taxes to that school district, only to the one I live in!).... it's a rip off.
School vouchers is the way to go. And get rid of the Department of Education!