My college considered dropping its PE requirement back in the 70s. From what I heard, a major reason for not doing so was because all the PE teachers were tenured and couldn't be laid off.
It was well-known that your performance on class work meant very little, and your only opportunity to get a good grade was to bet on the extra credit "opportunities" that arose towards the end of the year. Basically, it all depended on how much she liked you. One girl gave her a ride to the airport and her grade miraculously jumped to a 4.0 after nearly failing every assignment.
She also happened to be the chair of the AP committee, and tenured. It wasn't until well after I graduated that the school was finally able to do something about her, which amounted to having her teach non-AP courses and removing her from the committee.