Because you are not a Communist.
Because the "customer service" model of education is the easiest one to understand.
Because forgiveness is way too easy.
Because they have been seduced to dark and evil ways through exposure to the satanic influence of J K Rowling.
Because Katie you are not.
Where wast thou when I laid the foundations of the earth?
I mean, really, 'cause I saw you check in, but then you weren't there? Were you hanging by the bar with the Alpha Phis or what?
Because they were conceived in Original Sin, sinful and unclean, of course. That, and too many of your colleagues allow it. I hope you're not one of them!
Well, the serpent tempted Eve and Eve tempted Adam, and it's all been downhill from there (see Frod's comment above). Alternate point of view: they aren't sinning against us or our institutions, only themselves (and anyone else who is paying their tuition). To claim otherwise is to violate the first rule of CM by caring more about their educations than they do.
Because they really truly think they can get away with it. Not necessarily because they think you are dumb, but because they think they are so smart. Sigh.