Does the Public Benefit from Special Education?

In defending taxation for public schooling statist apologists frequently argue that educated children benefit everyone in that they grow up to be more productive citizens. I reckon parents get most of the benefit from children and their subsidized education, but even if one buys the argument about public benefit, how can special education be justified? This is some of the most expensive education of all, and such kids will probably never amount to anything more than taking tickets for the Tilt'aWhirl, a job that requires no book learning.