The thing about trains is that they gain cost efficiency in exchange for a massive time penalty. In most cases, you have to truck your goods from a warehouse to a rail center, unload them from the trailer to a rail car, wait for the entire train to be loaded and prepped, wait for a slot on the rail network, travel at normally ~45mph, and then do the reverse at the destination rail center. A trucking hub can swap a trailer in maybe 10 minutes and there's no need to group shipments together - you can send a single trailer load of stuff from point A to point B with minimal interruptions just like with a normal truck today.