We wait for the reason why. A child must be taught to look for the plans of the characters he meets. He must learn to question their motives and see the larger picture. This is a very difficult thing for a child to learn. It involves a new point of view for him.
Young children tend to accept the people they meet on face value.
They trust everybody. They do not see or look for sinister plans or plots. Most, if not all, plots are based on the interaction and blocking of some characters' plans as they strive to achieve their goals. Tracking such things in detail is often beyond a child's experience. He must learn how.