When a school owns the stadium, they get all ancillary revenues: concessions, parking, and stadium advertisements. 100% of the ticket price goes to school revenue. When you lease a stadium, you have to pay a percentage of each ticket sale to the stadium, and you may or may not get some of the ancillary revenues.
Texas sells out 101,000 per home game and they have seven home games. You have to "donate" to the athletic department to get decent tickets.
USC does not sell out the L.A. Coliseum. They get between 80,000 and 90,000 per home game. They have six home games per year. They charge a little less per ticket and you don't have to "donate" to get tickets to away games or bowl games.
USC and Texas may have similar traditions, but that's where the similarity ends. Texas fans are more ardent than the fickle Los Angeles "fans."