Well that's partly human nature. People tend to remember and notice the negatives and tend to neglect to notice those things that are positive. When you're making mistakes more, people will be very critical of you but when you're doing what they "expect" it tends to go unnoticed more unless they are the types of people that work at really encouraging and complimenting people.

Think about the last bad experience you had at a store or anywhere. I bet you can recall one. Now try to think of one experience that was equally as memorable in a good way. It's hard to do. I don't know why but we just pay attention to the negative things more and keep them in mind for longer.