kEiThZ
Superstar
Japan has subsidized their high-speed rail network to the tune of 250Billion dollars (if I remember right). That is half of Canada's entire national debt. Japan's debt/GDP is around 150% and rising.
And Japan also has a significantly higher population density which would make air transport more of a challenge (higher traffic density, higher fuel consumption from short routes, inefficient use of premium land for airports, etc). We don't have that problem here, which conversely puts rail at a bit of a disadvantage. Though, perhaps we are reaching a tipping point.