Consider how differently the public treats physics and economics. Physicists can say that this week they think the universe has eleven dimensions, three of which are purple, and two of which are twisted clockwise, and reporters will quote them unskeptically, saying "Isn't that cool!" But if economists say, as they have for centuries, that a minimum wage raises unemployment, reporters treat them skeptically and feel they need to find a contrary quote to "balance" their story.
I see the same pattern with my students - they'll easily believe physics claims, but are very reluctant to entertain standard economics claims. They come to class with strong incorrect preconceptions about the social world. As Caplan emphasizes, the publics' problem with economics is not the things they don't know, it is the things they know that ain't so; they act not ignorant but cocksure of error.