1 mile of light rail in the U.S. today costs between 40-50 million dollars. Americans love their automobiles, resulting in low ridership on many mass-transit systems. This is perpetuated by the relatively low cost of gasoline in America. In Europe and Asia mass-transit is much more successful because prohibitive gasoline taxes make regular operation of a car a real financial burdon. Because of low ridership in the U.S., mass transit systems also do not pay for themselves.
Trucks are primarily cargo carriers.
However trucks are also the main destroyers of highways. In recent years the allowed axle weight for trucks has risen from 44,000lbs to 88,000lbs to 126,000lbs. Highways are not built to carry such capacity.