Roy,
Fair point about compulsory attendance laws, I suppose. But if one buys the primary argument for a state role in education, that it is needed to accompany the universal franchise, then one sees the practical problem here. It would be entirely unenforceable to say that parents need not educate their children so long as their children will not be voting. Among other things, parental authority has limits ? it cannot extend to making decisions on behalf of children that are binding once the children reach adulthood.
As long as compulsory education laws are not specific as to the means, allowing parents to decide how best to educate their children (including in private settings or at home) I think they are an appropriate expectation for all parents, much like requiring them to feed, clothe, and shelter their children. Totally unnecessary for the vast majority of parents, but necessary and proper with regard to a few.