NCAA academic standards are very strict and the end result has been higher GPAs on average than non-student athletes. Schools just can't admit anyone and allow them to play. There are high school GPA, SAT, college GPA, course hours in a specified major, etc. requirements they need to meet or maintain and none of them are particularly low. Star athletes are suspended, kicked out of the program, and kicked out of school all the time for failing to maintain these standards. Just look at Everett Golson, the QB who just lead Notre Dame to the National Championship Game. There are also rigorous standards of conduct athletes must adhere to. There is a fair likelihood that Johnny Football, Heisman winner Johnny Manziel, won't be playing football this year because he allegedly signed his name for money.
I personally think the NCAA goes way overboard but there is no real incentive for schools to turn a blind eye to any of this because the NCAA's penalties are so severe. Just look at Penn State's penalty from Sandusky's action.
Of cours all of this ignores that the average NCAA athlete is a nobody. Sure, Johnny Football is the biggest name is Texas sports but how many women's poll vaulters does anyone know?