Aren’t there far cheaper options for regular commuters? Here in Berlin, a single one-way ticket is €2.60, but a monthly is around €80. That’s less than a euro per ride for the average person that commutes by subway and uses it for some other trip every second day.

Trains are, unfortunately, rather expensive, at least compared to flying and to taking a car you already own. I believe fuel and vehicle taxes should increase to the point where they pay for most if not all of road construction costs. Contrary to popular opinion, large parts of those costs are currently financed from general taxation.

Because tracks and stations make up the bulk of the cost of train rides, increases in ridership have low marginal costs. Any move to get people to use trains would therefore tend to lower per-trip costs.