Command economies are simply inefficient. The US overuses highways for long haul trucking because trucks pay a lower percentage of infrastructure and externalities costs than trains do.
Barges are just another way to move cargo, if lower shipping costs are worth the investment they can pay for the majority of it.
Also because of the little-known Jones Act from 1920 which states that any shipping between US ports must be shipped solely aboard vessels that are U.S.-built, U.S.-citizen owned, and, registered in the U.S., which means crewed by Americans. It's incredibly expensive to ship anything domestically in the US even though the geography is quite good for it.
The Registered in the US bit seems like it would place it on an even footing with other forms of transportation which is definitely a good thing economically. U.S.-built and U.S.-citizen owned are presumably good to get rid of economically, though it has some national defense implications.
> The US overuses highways for long haul trucking because trucks pay a lower percentage of infrastructure and externalities costs than trains do.
Source? The US has a massive freight train industry. We have more railroad than any other country - and almost double second place (China). I guess "overuses" is subjective, but we use commercial freight way more than anyone else.
We don’t rank #1 by total freight, total fright miles, either of those per citizen, or percentage of fright carried by rail. We rank much worse in terms of passenger rail, or electrified rail.
Number of rail miles only really shows the size of the US not the utility of it’s rail network as we also have the largest road network. The relative lack of electrified rail demonstrates the issue, the US network is mostly single tracked which causes a lot of problems even with the total number of miles the utility of any given mile of track tends to be low.
To complete the triangle, if barges are subsidized more heavily than trains, some cargo will, as with your truck comparison, overuse the less-efficient transport, at cost to the general taxpayers.
Barges are just another way to move cargo, if lower shipping costs are worth the investment they can pay for the majority of it.