thats the thing though, a rail line can pay for itself, a road often can’t. Its easy to “create a new branch road” but when you add in all the externalized maintenance factors: policing traffic, emergencies, fueling stations, stormwater management, the costs per user, the costs per user per mile traveled, land use requirements per user (4 parking stalls per vehicle, multiple vehicles per person) etc.
They often cannot pay for themselves, hence why the subsidies are necessary and why things like big box stores with huge parking lots are a net drain on most communities (its not just the low wages)
If they could pay for themselves we’d see more companies that just build and rent private roads like train companies do.