The problem with many / most / all of the statements on funding of rail transport is that they are made in a vacuum. No one seems to include the "what does it cost if you don't" option. The alternative to building a rail project is normally either building more roads, in the case of local rail, or airport improvements in the case of long distance rail, or increased traffic congestion if the "do nothing" alternative, and traffic congestion does have a cost. In fact, traffic congestion is the determining factor in the need for new roads, other than those politically determined. By the way, many are the roads that were a "road to nowhere" or bridge to nowhere" when proposed, designed, and built that are now approaching their capacity. Usually this mud is throw around to score political points, and no, I do not have a specific project in mind.
The Taiwan High Speed Railway is a very good example of a rail system that is doing exactly what it was supposed to do.
Big picture: The in-country service airport in Taipei, and the one airport in Kaohsiung were both approaching capacity. In fact, were already capacity constrained. The major service lane was between these two points with flights about every 15 minutes. Only a couple of flights a day remain. Since these are now mostly gone congestion at both these airports is greatly reduced, and: more service is provided to other places from Taipei, and there are quite a few more international flights out of Kaohsiung, where before, leaving the country required a trip to the main international airport near Taipei.
Other important benefits: For a country that imports every drop of oil it consumes, a significant reduction in oil used for transportation, less noise near airports, less air pollution.
Maybe it is worth ading: One of the companies that was big in the Taiwan High Speed Rail Corporation owned two airline, one of them international and the other domestic. It appears that they determined that a project that significantly reduced the demand for their domestic airline was worth doing.
An aside: If you were to see the methods used to justify construction of any highway project, you would find that quite a bit of the econnomic benefit used to justify the project does not result in anybody getting a check that they were not getting before.