If only there was some mechanism for moving freight along a pre-defined route without the need for constant steering. Perhaps some sort of rails....
That may be in large part due to the substantial government subsidation of car/truck traffic through public roads, not the merits of one against the other.
http://archive.boston.com/ae/books/articles/2011/06/05/colla...
https://mises.org/library/crony-capitalism-and-transcontinen...
https://www.bts.gov/content/weight-shipments-transportation-...
https://amp.businessinsider.com/the-staggering-statistics-be...
1. (As others have mentioned) a lot of freight is intermodal so containers in particular shipped for long distances by train also travel by truck for the first and last X miles.
2. A lot of freight is relatively local in nature, so it makes more sense for it not to be intermodal.