Apparently he learned to do his homework. See, public education did him some good.
Unlikely, I know that in college I had next to no homework outside language classes; my math professors basically said, 'I assign homework because it is university policy, it is neither collected nor graded and I will not grade it even if you ask me to. They created the tests such that you could only pass them if you knew the material, if you went to class and did all assignments but still couldn't demonstrate proficiency on the exams you should, and did, fail. If you never went to class never did a bit of homework and only showed up for the few exams and aced them, then you would receive an A in the class. It really doesn't matter how you learn the subject, all that matters in the end is that you do learn it. Of course, I knew very few math students that could get away with skipping classes, I probably did it more than most but I still probably made 80% of my classes.
In the public school system, the problem with a few students is that the teachers teach towards the idiots in the class. I recall having weeks of lessons on a concept that I thought anyone should be able to get after an hour lecture; I never skipped class in high school, I was a pretty good student, but I would never pay attention either...I probably did so well because I used my lessons to do my homework for other classes, so I actually got it done but never at home.
Formal education does not always amount to education, intelligence, or teaching ability (especially teaching ability). But I do agree that those who truly have a passion for knowledge will go to school regardless of the cost or economic prospects (I did). It's not a fool-proof system but the current system at least gives a good baseline (though standardized tests should be more difficult by about a factor of 25; I don't know about Missouri, but I was going through practice tests for teachers with friend who is studying for them in California and I found that I was able to get a passing score on an entire range of subjects, I only hold degrees in Mathematics and Theology, with an undergraduate Minor in Computer Science; if I can pass the English, History, Biology, and Physics tests they are obviously to easy).