One reason that I think it was settled on in Japan specifically (and probably many place in Europe as well) was general war-induced poverty among the civilian population. People simply couldn't afford to buy nearly as many private cars because of the deprivation caused by the military situation. So it didn't make as much sense to build out a huge infrastructure for private motor vehicles when people couldn't afford to buy them. Japan underwent a long period in which most resources were going to the military and expansion, at the same crucial time in history where Americans were really starting to get serious about the car. The Japanese, by contrast, didn't really take off as a car culture until after WWII. So some of this is just a byproduct of the differing histories of nations. I believe a similar thing happened in Europe, due to the effects of WWI and WWII. I don't think it's so much a cultural thing, as it's a reflection of the different paths those nations chose to take.