You can look at the 2005 team or any of the teams that played in a 20+ year window at North Carolina. How can the NCAA bust UNC-Greensboro for having athletes that were ineligible college students with a brief investigation? Then the UNC AfAm scandal has taken so long, years, because there was so much cheating. Now they get nothing?
It's all about money and perception. If the NCAA punished UNC, it would be the first time they've had to vacate a national championship(s). That would definitely damage the perception of the "student-athlete." Which in-turn would damage the NCAA's money.
The message the NCAA is sending with not punishing UNC is if you're going to cheat, do it on the largest scale possible. Why even go to class? Just make class rebounding or foul shooting or playbook study. The education side of the NCAA is pathetic and there is no wonder that top-level student athletes influence our society with their uneducated thoughts. If only there was a system that made them go to a REAL class every once in awhile.