There’s really a two tiered structure to academia that seems to be hidden from most students. Maybe even 3 tiered. There’s the tenure-track research faculty who might teach one class per semester (often less) - they’re still underpaid relative to industry equivalent jobs, but they get their research freedom and low six figures after a few years while bringing in seven figure research grants for the university. Mid-six-figures if they’re upper admin. There’s non-tenure-track adjuncts & academic professionals who teach 3-5 classes per semester, often at multiple universities because no one will give them enough classes to live on, doing the bulk of a university’s teaching, especially at ‘tier 1 research’ universities, and they’re lucky to get median salary. There’s also a set of tenure-track faculty at universities without big research programs who teach 2-3 classes, maybe do a little bit of research or literature review, but probably without any significant extramural funding. They get paid somewhere in between.

They all get called “professor;” they all have PhDs; there’s infighting to keep the faculty as a whole from rising up. I used to tell my students they (or someone on their bahalf) paid about $200 for each of my lectures, and they’re free to skip them if they want, but even in a tiny seminar, 10 students, $2000/hour revenue, the highest paid professors are only getting 5% of that (not accounting for out-of-class effort).