I don’t know why football coaches would be paid more than basketball or baseball coaches at the high school level (other than competition), but it makes perfect sense to me that coaches would be paid a lot more than teachers who are not coaches. Coaches are required to be gone from home and work after normal hours FAR more than non-coach teachers. I know some non-head coach Texas HS football coaches that put in 80-90 hours a week between coaching, teaching and team travel during football season. It’s insane.
Also, I’m not as up on this as I used to be, but a lot of times the head football coach is also the athletic director responsible for all sports at the school.