This man’s position, and thousands like him across the country, could be replaced by a single DVD.
It could, IF you could get credit for taking a course by DVD and taking proctored tests, and do so at a cost in line with the expense. However, at the University of Arizona, for example, distance learning costs the same as attending by class.
A 5 credit calculus class online cost, IIRC, roughly $3000. The local community college offers it in person for <$300.
But online, the class should not cost more than the community college. Tests are administered by someone else, graded by grad students, and any questions probably answered by grad students as well. Done as an online chat, one person should be able to answer questions for a class of 100, while the lectures themselves could be loaded on YouTube.
However, I’d bet you couldn’t get accreditation for classes taught online that way, because it would overthrow the University system.