The capacity of a fully loaded conventional HSR line is massive. The Beijing-Shanghai HSR route (a northbound and a southbound track on a right of way 20 meter

The capacity of a fully loaded conventional HSR line is massive. The Beijing-Shanghai HSR route (a northbound and a southbound track on a right of way 20 meters wide) and every UK airport combined, carried about the same number of passengers every year before COVID, just above 200 million. We can make conscious choices about whether we want comfortable accommodations or cattle cars, and cattle cars are what we ask for when we say "Absolute minimum capex on rolling stock" and "We're going to size passenger station platforms for 6 cars instead of for 20 cars". If you are running 10 million passengers per year, but still running rolling stock that will fully utilize the capacity of the rairoad, you can afford to use space 20x less efficiently than the Beijing-Shanghai HSR line does.