Even ignoring land acquisition (which is a big thing to ignore in populated areas where a train would most benefit the population), there are simple things like road crossings, other infrastructure crossing, etc.
In this case an airplane may be simply a lower friction solution.
I lived in the UK for a few years, so I can appreciate and really enjoy a robust rail network, but it’s not an easy thing to achieve.
This I don't get. I've seen rail stops in the smallest towns, where the train stops for 30 seconds to let a couple people on or off. Places where even the smallest airplane makes no sense at all. Not 30-100, 1-2.
That being said... federally supported rail is still far more economical than flight. It almost has to be: the train doesn't need to lift off the ground.
(Why is it in Star Wars' universe that every 2-bit peasant owns permanently levitating "cars", but can't afford adequate lighting in their hovel?)