Books provide a primitive form of automated teaching, although we've expanded on the concept considerably since the advent of the book.

You have not heard of automated teaching as a thing because we invent names for automation. The automated kitchen servant isn't called an automated kitchen servant, it's called a dishwasher (among others).

Likewise, automated teachers are not called automated teachers. They are given names, depending on the teaching method at play. Automated teacher is used here as a generalization as the specific automation is immaterial.