I teach in a university mathematics department. I don't doubt that stories like this are real, but very few of my colleagues collude with, or indeed have much patience with, the publishing industry. Indeed, the opposite is common. Walter Rudin is the author of several well-known books on mathematical analysis. The publisher, McGraw-Hill, jacked up the price of his books to stratospheric levels, and Rudin fought back…
Kudos on him for valuing the spread of his work over any personal loss in royalties!