The population density of a whole massive country like the USA doesn't matter for public transportation that reaches its largest cities, you have pockets of ver

The population density of a whole massive country like the USA doesn't matter for public transportation that reaches its largest cities, you have pockets of very high density and an immense flyover space where few people live. With the density of the Northeast Corridor you could have the exact same setup as the Netherlands has, the Northeast is only 20% less dense than the Netherlands while housing 50m people, there's almost a whole France in there but nowhere close to the infrastructure the Netherlands nor France have to move people around. The USA is massive so there's a lot more space for localised solutions that work for different parts of the country, the West and East coasts could have similar solutions to interconnect the whole N -> S, there's enough density for it. If Sweden with 10m people and a frigid climate can run trains, public transportation, etc. in all major population areas along an area equivalent to the whole West Coast then I don't see any reason, except cultural-political ones, the USA couldn't.