[beerandt]

If rail isn't profitable due to lack of demand, it likely also isn't environmentally friendly.

The rail efficiency sold to the public is based on projections that (generally) also made them profitable.

Rail efficiency decreases drastically as usage declines, as so much of the embedded energy and emissions is in the fixed cost of building out ROW and track, and ongoing MOW.

You need to operate at a high percentage of capacity in passengers per train, and high percentage of capacity in trains per track.

Efficient rail systems are relatively a highly constrained problem, due to said fixed cost of track, but also due to lack of flexibility to adapt to changes, both in routes (need to move/add track) and capacity (track at full capacity doesn't meet demand, but two tracks exceeds demand at cost of being inefficient). (Operating one track that doesn't fully meet demand increases prices and becomes an expensive but profitable point of stability.)

Which is why eg high-speed rail proposals in the US typically rely primarily on improving existing slow routes, and are limited to midrange distances. Too short and too long both push it to being more costly at reduced efficiency.