> Assuming we go in a perfectly straight line (trains can't do this) and no stops

I looked it up out of curiosity. To travel the length of Japan's bullet train network, which goes most of the length of the country, it takes 3 trains and 31 stops, for a total of just under 12 hours. A flight between the same locations is just over 3 and a half hours.

For those who want to look it up, these figures are for Kagoshima-Chuo Station to Shin-Hakodate Hokuto Station.

I can see how the train would be come out ahead for shorter distances, but I think this kind of trip is more reasonable of a comparison with the distance of flights that many Americans are taking.