exactly. even under communism/socialism, a business must still operate at least somewhat meaningfully. it can't just be "trains for the sake of trains". there has to be a meaningful number of people served per km of rail. that's why it makes sense near the coastlines.

also, short reminder that even if a rail goes at 200 mph, it would still take around 15 hours to travel the 3000 miles from east to west coast. almost nobody is willing to sit in a train for 15 hours straight. at that distance, most people prefer an airplane. it's significantly faster.

i did some quick maths and calculated that at least in europe, for distances greater than ~800 km (~600 miles), an airplane is mostly faster than a train, at least in western europe.