Or that business simply gives small preferred publishing deals to the Dean's professors. Often these professors have their own books that are required for the class (and nobody else uses these books).

You end up with books that sell < 100 copies a year that would never be published from a market demand perspective but provide extra $ for the professor (which matters to the Dean for retention and salary).

I graduated from a large state university engineering school 20 years ago and this was the case so I'm sure it's only become more "enshittified".

FYI, this has been going on since at least the 70s. Assigned text of sub-standard quality in one of my classes had been recently written by a prof at a neighboring college.