Yeah, you're in SEC country so it's not as rampant. But I'm used to the Non-Power 5 Conferences where every dollar towards the program goes a long way. Any six-figure donation to a non-power 5 football program by a parent with a child should easily see said child on the football team or really any athletic program/team.
Even at USC, there are many kids who have parents like team doctors or physicians of staff. It's like their kids are already enrolled, and they may want to have a 'hobby' while in college. So you played high school football, weren't any good but go into USC because of previous generations and you're next. So not only will the uni continue the family legacy, but the family will donate a shitload of money to the athletic department (tax break, exclusive donor benefits, etc.) and low and behold the kid is on the football team.