One of the main reasons that Americans were willing to pay school tax, particularly at the beginning of push for compulsory education provided by the state, was that it was against the law not to do so. Compulsory education was a policy that was pursued by a powerful elite and then forced on communities starting in the state of Massachussetts.
Currently there are other motivations, though the fact that tax evasion does not appeal to most people remains a large one. A good school district increases property values for everyone, regardless of whether they have children in school or not. Good schools have also been shown to create all kinds of economic positives for the communities around them.