And you've got standardisation, across an entire rail ecosystm (that's rail, not Rails), in which locomotives, rolling stock, couplings, etc., etc., etc., all need to work together.

An advantage of standardisation is you get, well, standardisation. Such as US President Herbert Hoover implemented by setting up the National Institute for Standards and Technology (NIST), which specified standards for screws and nuts and bolts. I'm not sure if Bendix transmissions were included, but come WWII, it was possible for the US War Department to order something like five million Jeep transmissions from several dozen suppliers, any of which could (at least in theory) be interchanged or have parts swapped between them.

The disadvantage is that you may find yourself very effectively stuck at a local optimum that's far from a global optimum, with murderous path dependencies.

I've been grousing over a set of TV propaganda videos created by the Mont Pelerin Society / Cato Institution through Johan Norberg and his "Free to Choose Media" production company (at least the propaganda slant is fairly obvious). The 2nd installement of his series on Adam Smith spends much of its time aboard a supersized cargo carrier, waxing rhapsodic about the wonders of the market in coming up with such a marvelously efficient system.

Except that it took the US Navy to standardise container sizes. After some 20 years of dickering over container sizes, materiel transport needs of the Vietnam War finally forced standarisation.

(Another US regulatory body, the Interstate Commerce Commission, meanwhile, had been happily impeding progress thanks to its regulatory capture by the railroad industry, and I won't even begin to mention the Texas Railroad Commission, which has little to do with railroads and was exceptionally significant well beyond Texas, at least for a time).