If you made the argument that the entire tuition cost is say, 80k, and they divided it evenly into 20k/yr x 4 rather than 25k + 25k + 25k + 5k, that would be fair. Maybe that's how it actually is planned, but it doesn't seem that's how they represent it.
You are better off with the 20k x 4. They are doing you a favor. Why complain about it. Google time value of money.