The difference comes from the fact that smart Europeans graduate secondary school with the equivalent of an American university grad's education. U.S. universities must therefore offer more coursework in order to bring their postgrads up to snuff with what's expected of a fresh university grad in the rest of the developed world.
Having lived in Europe for almost twenty years, with a spouse teaching in a European secondary school, and with the utmost respect to my European colleagues, please allow me to assure you that this is not even remotely the case.
Having grown up in the USA, gone through the "second high school" USA university system, and heard reports from personal acquaintances and sites like this one on what levels of math German and Russian students graduate with, I'm still gonna press X to doubt the truth of your assurance, as earnest and well-meaning as it may be.
