I actually educated a young principal way back when. I pointed out to him that the parent knew that they should call me. They also knew what the answer would probably be, but they had no interest in hearing that answer. So they call you (the principal), along with their neighbor, the superintendent's secretary that they go to church with, etc. because what they really want to do is vent and gripe. They know you (the principal) do not have the answer, but you also are not in a position to refute their gripe. They will eventually get their answer from me, and they won't like it, but in their mind they 'made trouble' for me because the principal probably said, "Oh my. I appreciate your concern and I will look into that," and their neighbor and the sup's secretary probably agreed with them to get them to shut up. And in some cases with a weak administrator they just might actually cause me a problem, but it won't change my answer.