True, in 1950, $4000 was good. Unfortunately, I got that in the 1970s (which is one reason I left.) Even tenured professors teach 4-5 courses/semester (of 20 to 100 students) and grade their own papers. Things are supposed to be better now.
Things aren't better now for the nomads, the part-timers who teach for $2200 a course and zero benefits. That's three times a week for 14 or 15 weeks and sometimes the classes have 150 or 200 in them. For this the parents pay $40,000 a year!
What do you do now?