> The cost of passenger rail is high in America, because America doesn't build enough rail.

The cost of passenger rail is high in America because America has 11% of the population (read: customer) density of Japan.

(For cities, NYC has 25% lower population density than Tokyo.)

Dividing population by total land area is a horribly misleading way to understand density. There are alternatives, like population-weighted density, that give you a better picture: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3119965 Here's a blog post where somebody re-invented the concept and analyzed density in Europe: https://theconversation.com/think-your-country-is-crowded-th...

The population-weighted density of the US is roughly similar to continental Europe.