And it does strike me as weird that I have a lot of friends from third world countries that come here because they view America as the land of entrepreneurial opportunity, when this study shows that they would be much better off in Germany.
There are factors that are equally or even more important, like taxes, availability of capital, bureaucratic hurdles etc. I once heard from a German restaurant owner that he fought 12 years to get a permission to put tables in the garden...
Another factor might be that it's possible to get accepted as an American in a few years. In Germany you may be a naturalized citizen on paper--but the real social acceptance of compatriots runs through bloodlines. (I.e. you have to look the part, too.)
Not that they won't be nice to you. But your children will stay, say, "Turks" in the third generation and onwards.