Immagine
Jock Walks up to super geek
Jock: "Alright. I will pay you $2,000 if you go to every one of my classes and Take My SAT's For Me."
Super Geek: *thinking* 'Hmm.. I can build a pretty decent computer with 2,000 dollars...' "Done."
Super Geek takes test, gets perfect score for Jock.
Thats why they would need IDs, Whats to say the person thats been to class is really the person thats supposed to be there lol