The key reason: variability!
Sometimes a blueberry is perfectly blue, cold, and round; sometimes it is not. Sometimes an avocado is green, room temperature and mushy; sometimes it is not. As adults, we are aware of this inconsistency in produce, and our level of cognition enables us to recognize this. However, to many children this variability is troublesome. A blueberry at school may be different from a blueberry at home!
Hence, foods like Goldfish, Wheat Thins, or Doritos often become preferred foods since their presentation is typically very consistent.
If you are concerned about your child's eating habits, please call Speech By The Beach Consulting LLC at 239-631-1988.