A major part of this problem is teachers who treat "student knows something I don't (or aren't prepared to teach right now)" as a status challenge to be rapidly obliterated, rather than as an opportunity to encourage a student.
Many, many adults are extremely emotionally unprepared to accept the possibility that they may be wrong and a child may be right; they start from the assumption that this is an impossibility, and reason backwards from there.
Or, in the case where they do in fact know that the child is right, they nonetheless decide to prioritize asserting authority over demonstrating how a mature adult should handle being wrong. And thus do students learn bad examples of what to do when they're wrong.
Many, many adults are extremely emotionally unprepared to accept the possibility that they may be wrong and a child may be right; they start from the assumption that this is an impossibility, and reason backwards from there.
Or, in the case where they do in fact know that the child is right, they nonetheless decide to prioritize asserting authority over demonstrating how a mature adult should handle being wrong. And thus do students learn bad examples of what to do when they're wrong.