That article talks about multinational companies, not individuals. In other words, American companies are more productive instead of American software engineers

That article talks about multinational companies, not individuals. In other words, American companies are more productive instead of American software engineers being more productive. That could very well be due to differences in management and in fact that seems to be the conclusion drawn by your link, which states that productivity among European companies increases when those companies are taken over by American firms. Right from the abstract: >US IT related productivity advantage is primarily due to its tougher "people management" practices