We also have access to airplanes, but that would be a very ineffective way of shipping. Rail is still by far the cheapest way to move a bulk commodity. Speaking for grains, it's not an option to truck grain to the coast. It would be far more expensive. In a monopolistic environment with no competitors, the only way to stop a monopoly carrier from charging the very maximum price they can is through regulation. In a perfect world, there would be competition, so efficiencies would be bred into the system.
Speaking for grain farmers, it's not an option to truck grain to the coast.