Optimal transport methods are very much still in use in economics. The show up in two-sided matching with side-payments, contract theory, hedonic pricing, partial identification in econometrics, and a couple of other areas. You can find an excellent overview of economic applications in the 2016 book Optimal Transport Methods in Economics by Alfred Galichon.
The world bank group has a Urban Transport Data Analysis Tool (UT-DAT) located here: https://www.worldbank.org/en/topic/transport/publication/urban-transport-data-analysis-tool-ut-dat1
It has an excel file that has some data. There is also Data.world https://data.world/datasets/transportation
There is Global Mass Transit website but its a paid service ...
The paper "The impact of scale on energy intensity in freight transportation" by Gucwa and Schaefer has some of the information you need. Figure 5 from that paper is presented below:
The site ShipMap.Org has a data visualisation of shipping routes, where you can filter by type of freight.
(Disclosure: these are all colleagues of mine except Gucwa)
Though these are only educated guesses (contract law is not my forte) I'd suppose that there might be a few reasons why this is:
It's best able to handle the competing interests of the parties involved. Historically, the US Federal Government was more willing to grant public lands to railroads (particularly in the little-settled west). However, due to ...