The USA already moves a higher percentage of freight by rail than almost any other country. But rail could never work for time-sensitive loads or last mile delivery.
Perhaps they could make the rail lines and machinery smaller. One might even consider such rail to be "light", in comparison.
I'm sure it's pure coincidence that many cities already have rail lines going down roads in city centers. They probably just built the city around a historical freight line, and haven't bothered to remove it.
Last mile I will give you. Those shippers use trailers and containers on railroad cars, and trucks do the last mile delivery.