The Dreaded Peer Review

What is it about having one's peers review a person's work that is disconcerting? It has never bothered me to have a teacher or professor read my work, even in its most infantile stages. This is in sharp contrast to how I feel about having my classmates review my work, even if it's finished. I have a tendency to want only expert opinions regarding my work. I am a perfectionist; I have a very hard time letting go and letting others take control of a situation...any situation. To me, the peer review process is an exercise in tolerance and uncomfortability. It's more psychological for me than academic. Nonetheless, regardless of the benefit, I realize that it will make me a better, more well-rounded person. Simply by experiencing something new and uncomfortable, I am conditioning myself to be more receptive to others' assistance.