People obsess about making sure that trains are full. Talk about moving warm air around during quieter periods of the day. Yet noone seems to point out the main competitor to rail travel involves traveling with a pair of arm chairs and a sofa, with a total number of passengers of 1. The inefficiencies of private cars are ridiculous.
As long as the whole train network, across the whole year and all services is >20% occupancy, it's more efficient than the competition.