Ok, then the problem with such projects in the US is obviously the lack of plannability. New York has now (finally, after decades of planning) built 3 stations

Ok, then the problem with such projects in the US is obviously the lack of plannability. New York has now (finally, after decades of planning) built 3 stations of the Second Avenue Subway. Wether it will ever be expanded is currently unsure. Compare that to Munich, where between 1965 and 2010 there was always a subway under construction. Even without the inherent interests of the companies and workers involved, it should be obvious that when you build more, the cost per mile will be much lower.