This is just guessing, but I'd think population density plays a major factor. I'm just eyeballing this list here [1], but Japan is roughly 10x as dense populati

This is just guessing, but I'd think population density plays a major factor. I'm just eyeballing this list here [1], but Japan is roughly 10x as dense population wise as the US. 1 - https://simple.wikipedia.org/wiki/List_of_countries_by_population_density https://simple.wikipedia.org/wiki/List_of_countries_by_popul...