It's very simple: they cannot solve difficult problems. They cannot do any task that requires them to put together 2 or more concepts. And the reason they cannot do this is very simple: Everyone gets good grades. And they feel good about themselves. The teachers tell them exactly what will be on the exams, they memorize that, and regurgitate it.
BTW: Euclidean geometry is no longer taught in many high schools. It just isn't "useful." Which I find ironic, considering a few very famous lawyers, such as A. Lincoln and J. Garfield knew Euclid by heart.
They have them using the mathematical concepts of Euclidean Geometry as early as the 5th grade, without questioning the "why" of things.
No alphas, plenty of betas...
What I really don't like is these BRAVE NEW WORLD kids aren't asked to question or justify anything.