Even though railroads are much more energy efficient and deliver lower transportation costs without federal subsidies, why are trucks the preferred mode of transportation?

I think that the answer lies in the fact that the highway truck combination is effectively open source.  The term open source is commonly used in the software world, but it applies here as well.

The platform is a highway, which just about anybody can use, provided they obey rules for weight, size, and safety of their modules (trucks in this case). This gives a tremendous amount of freedom to truckers and shippers to control their own destiny.  Ask anybody who has used the railroads for shipping and you will see that a rigid central planning department controls how and when your freight arrives.

How about this for an idea. Let’s make the railroads into a regulated monopoly. (It works for electricity, water, and gas BTW). The railroad makes its income by maintaining the infrastructure.