I think there are two questions.
One, would it make sense at the federal level to build it for a specific region? In the end, yes, because we can increase GDP. All these investments have a positive multiplier from a macroeconomic perspective.
On the other question, it makes no sense to build railways in areas where no people live. There are some exceptions in France, where you have a distance of 200 kilometres or 300 kilometres without a stop between two cities, but I would say that this is more or less the longest stretch that makes sense.
If you have, for example, a stretch that is 500 kilometres or 700 kilometres, that distance would be much too far when we talk about the electrification of airplanes or whatever, which would make much more sense from a transport mode choice.