This is not about the teaching discipline. I am a Computer Science adjunct, and the salary I get from teaching is equivalent to what the article mentions.
I only do this because I like teaching, so this is not my main source of income. I am not in the verge of homelessness because I do programming for a living. But the problem is still the same: Universities are charging astronomical tuitions and then paying a laughable part of them to teachers.
It does not make any sense, and IMO that explains in part why University education is losing its value: you get overworked and unmotivated teachers as a student, so you may better learn your stuff online.