When I attended the University of California at Berkeley in the fun 1960's, there was no tuition for in-state students. Zero. There were 27,000 students at that time just at that one campus.

It would be hard to quantify the return on investment to the taxpayers, but free quality higher education must have contributed to the thriving California economy and culture.

Of course, our costly rival Stanford has also contributed much, to Silicon Valley in particular. But we have twice as many Nobel laureates :)