Jesus, dramatic much?
It's actually really simple; if the student is not hurting or harming anyone, and is not being disruptive in any way, then who the hell cares? Don't punish the kids if they aren't being harmful and/or disruptive and get rid of the rule or re-write it accordingly.
You're right - on a day-to-day basis, no teacher is going to waste their time policing facial hair that's not a distraction. Same with the majority of administration.
But when you host a graduation, and are spending tons of hours and money on a ceremony that will be attended by alumni, board members, feeder-school admins, director of high-schools, not to mention the parents and families, etc...yeah, I can imagine the students are held to a higher standard if just for one evening.
Personal Anecdote - the Superintendent of schools is NOT checking students as they enter and prepare for the walk. At graduation two weeks ago, I saw a student kept out of the gate because he didn't have a tie. A teacher brought extras because even though students are given instructions well in advance, and conduct and actual rehearsal, you can still count on students to forget stuff or try bringing in contraband.
I can only assume, but I'd put money on more than one teacher at that school giving the VALEDICTORIAN a heads up on them having to enforce the facial hair rule at graduation. 14 students understood (begrudgingly or not, who knows), that even though some rules suck, breaking them still brings consequences.