You calculate costs: engineering hours × price of engineering + steel tons × price of steel

…and you’ve left aside all externalities that don’t matter to your profit: Economic benefits from joining high population-density urban areas or industries, environmental impact, social cost of nationalization (how will you as a private company nationalize the land for the railroad?)… Now you have a society where there’s a disconnect between the providers of a necessary service as transport, and its users. Efficient as FUCK.