There are ways to combat that as well. My oldest went to U of Montana. Football tix were free for up to the first 2,000 students, but they had to go to the ticket office on Tuesday morning of game week to claim their spot. If they failed to show for the game, they lost their privilege (it was all tracked on their ID cards). They also had the option of buying their season tix and avoid all of that, which also gave them a ticket for their rival, Montana St, which was always a sell out and not part of the free package. It also let the university put the unclaimed tix up for sale mid week.
Btw, they draw pretty well and their student section is pretty full and rowdy at game time.
I too am disgusted with the amount of fans who don't care to be in their seats for the teams coming out, or for the first quarter for that matter.