Schools have a different obligation than the NFL, namely, to the entire student body and employees. The NFL really doesn't give a rat's behind about the public at large, so long as they can get enough butts in the seats. Otherwise, they would test even vaxxed players (who can still transmit covid to others) before they come into contact with fans through public appearances, etc.
From what I've read,intercollegiate athletes,staff etc. are subject to more frequent Covid testing then other students,staff,employees etc.
If this isn't the case let me know.
If it is the case,then, based on their "obligation" ,schools should be requiring the same Covid testing for all students, faculty and staff,not just intercollegiate athletes.