There's a few premises which I suspect are true:
People who aren't practiced in thinking would have to invent a method for solving a particular problem from scratch. Therefore, they would take much longer to find a solution.
Those who have success using shortcuts will trust those shortcuts. If they used them and didn't have success over the years in most circumstances, then there's be no positive reinforcement to reward their use.
I've witnessed engineers and carpenters teaching each other shortcuts for normal workday problems. One of the best exchanges I remember even now was at a job while in my twenties, when there was a corner fix needed on a construction job. One guy told the foreman that something could be accomplished easily. The foreman gave the guy a pencil and said, "Teach me something." I thought that was brilliant, and have always used such situations at work as learning opportunities ever since.
Let's take the two ends of the spectrum, Albert Einstein and that chick who couldn't do math to save her life. Remember her?
Which one do you think is going to have more confidence in their answer on a math problem? Obviously Einstein would have experience at doing math correctly, so he's going to assume he's better than Dim Girl.
I think they're looking at a narrow group while doing this testing, and unless they're trying to say that members of the Westboro Bible Church are all geniuses, I think their conclusions are mistaken.
But maybe I'm biased.