You should think that the cost is basically per floor area. The cars are already as light as they are willing to go (for crash safety etc). The minimum acceptab

You should think that the cost is basically per floor area. The cars are already as light as they are willing to go (for crash safety etc). The minimum acceptable space gets you to a price that a trainload of people per day can afford. The beds with their own screens look nicer than the ones in trains I've taken (and at comparable density) and far far nicer than anything in the air I've ever had. (Also nicer than the airport lounges I've slept in between flights...) There are also private cabins which I'm sure cost double.