A human understands what they're saying. If a human teacher is working through a math problem and isn't sure of their work, they're able to stop and correct their mistake. An AI math teacher is trained on a corpus of data - probably very similar to the data that the human teacher was trained on, though I'm sure the AI was trained on far more data than any single human ever was - but can't do the introspective part. To put it another way, I think we agree that humans learn better by assessing multiple sources and thinking critically. An AI is very good at the former, but very bad at the latter, and I would rather have a teacher that can think critically about what it is saying to me.
