Historical context:
There was a time in the past when railroads hauled freight in less-than-carload lots (LCL). Pickup and delivery was handled in local freight trains. Freight houses were kept busy moving partial loads from one car to another at various points. This was an extremely labor intensive and low-profit business. As the highway system improved and the trucking industry developed, it became much more efficient to ship these small loads by truck. By the late 1940's, the LCL business was in decline. By the 1960's it was certainly dying and in many cases already dead. I doubt that any railroad was still offering LCL service in the 1970's. That's when Amtrak started.
In the days of LCL, railroads offered Express service. These were expedited shipments of very small quantities, handled by specialized Express companies such as the Railway Express Agency, Adams Express, and others. Fresh flowers, live chicks, holiday gifts, bodies in coffins, newspapers and magazines, and lots of other important, timely shipments were often handled like this. These shipments usually traveled in passenger cars, very much like the handling of mail or even passengers' baggage. There were even specialized express cars designed to carry racehorses or large scenery for traveling shows.
All of this was quite separate from regular freight service, which concentrated on large quantities that required one or two (or a hundred) full freight cars.
Nowadays the large railroads have concentrated on the large shipments. They left LCL to the truckers, express to FedEx and UPS, and passengers to the airlines.
If the big railroads don't want these small shipments, and if Amtrak can handle them at a profit, it makes sense for Amtrak to do that. However, the large railroads did have a point in their objection to Amtrak's hauling of Roadrailers, which were a type of freight cars that could be considered competition with the host railroad.
Tom
