Children are at a disadvantage, because they are usually forbidden to be plain-spoken and critical of their parents. They depend on their parents for food, shelter - everything! They also love their parents more than anyone else in the world. For all these reasons, disapproval from a parent is especially painful.
Being just like us, if the pain is sharp enough, they will try to hide it. It's hard to say. "I need you. Please don't be mad at me!"