Why Aren't More Classes Taught the Recordings of Super Star Teachers?

Why aren't more classes taught the recordings of super star teachers? Sarah hart could take high school geometry lectures that would inspire mat students around the world. Mympial could teach oa science. Is it really such a crazy idea? A hundred and 30 years ago, people were entertained by live sic produced at home. But with the arrival of recording technology, society moved to a different model. Why didn't the same shift have an education? I don't know, but maybe it should. We can be reached at pima at freconomics dot com.