They do get paid. It just isn't in the form of a paycheck.
People who argue that the universities are making millions off these athletes are missing the actual relationship here. Those millions go to stadium improvements, better equipment, better coaches, more wins, and thus more exposure. Big moneyed programs get seen and that's what players want. It's a reciprocal relationship, and players benefit from all that money, too.
The fact that we can't just say they get an education, all expenses paid, and that's enough really devalues education, IMO.