I think it's the "Say no and maybe they'll go away" philosophy of dealing with problems.
I once worked at a company with a computer specialist whose first response to any request was ALWAYS, "It can't be done." The more annoyed you were by that answer, the more likely you were to get a "Well, okay" instead. I think he learned that saying "no" lightened his workload, so he just issued a blanket "no" without even listening to the question. A good bit of the time, people just accepted it.
I suspect the exact same thing is going on in a lot of schools...
