Why such a pervasive incidence simplistic thinking?

I have long suspected that our education system, with it's emphasis of getting the one, right answer contributes to the tendency of people to think simplistically, to stop thinking about things at the first thought they think of or are presented with, and not think more deeply, about other possibilities and contributing factors. It occurred to me a few minutes ago that the use of timed tests probably contributes to this.

Another factor would be the fact that sociologists who study different cultures found that the U.S. is one of, if not the most, highly competitive cultures, in the sense of feeling you have to be the single winner, or you are a loser. So if you acknowledge that something you have learned or believed is not totally true, you feel as if it makes you a failure.