Yeah, I think even if most rural residents would want a rural expressway over train service, there's a certain amount of people that can't drive or can't afford to own a vehicle. Given how much tax money goes into roads (beyond that collected via gas tax,) it seems fair to make sure everyone can get places even if they can't use the roads with their own vehicle.
That said, depending on the cost I think there's an argument to be made that most of those people would rather see a few well-timed buses connecting them throughout their region, with connections available to nationwide bus, rail, and air networks, versus having an once-a-day train, especially if that train stops in the middle of the night. That, however, would require us making a strong effort to build those connections and making it simple to use, and having it coordinated much more than the rural intercity bus subsidies currently are. It'd also still require a network for people to connect to, and having no rail network connecting the East Coast to Chicago, or Chicago to the West Coast, would make that a difficult proposition.