Airports aren't nationalized in the USA. They are usually set up by local governments to facilitate trade.

Yes, we probably should have.

But meanwhile, my point was that due to their inflexibility you absolutely cannot operate rail vehicles without the ancillary equipment required to perform certain tasks. It's not as easy as saying, "It costs x per mile for railroad tracks therefore everything should be trains." That doesn't tell the whole story, and all of those add-ons are, in fact, mandatory.

With a steerable roadgoaing vehicle you can work around much of it if necessary. Rest areas and even traffic controls and guard rails are not actually technically necessary for a vehicle to successfully go down the road and you can wing it re: parking lots by parking in the dirt if you have to, and so on. The whole arrangement would certainly be horrid without those things but it can and does still work. There are thousands of miles of rural roads in America alone that are served by absolutely no external infrastructure except stationary signs and some guard rails.

However, you cannot turn a locomotive around no matter how much redneck creativity you apply unless you have turntable, a loop track with a switch, or a big crane... period. You cannot add or remove cars from a train without a long enough spur or a railyard, and in many cases a second "yard" locomotive, period. You cannot have one train pass another without a siding, period. You cannot store currently unused cars without a railyard full of tracks, period. A train cannot change tracks without a switch and someone (or some computer) to man it, period. Etc., etc.

During the initial railroad boom this was actually a very real problem. Anyone who was anyone and who was rich enough wanted to have their own little spur railway going to their factory or estate, and it turned out that the logistical clusterfuck and ancillary equipment needed to serve all of those individual low volume needs was so expensive and was such a hassle that the very moment trucks were viable the huge majority of all those little endpoints were abandoned and demolished pretty much overnight. Rail has an insurmountable problem with the final mile, and the more individual locations it has to serve the more untenable the ballooning cost becomes in both money and space, which must be counterbalanced by a sufficient economic benefit.

Where trains excel is by moving a whole shitload of people or product from one source to one destination, which unsurprisingly is almost exclusively how they are used outside of the context of intra-city people movers like subways and surface light rail. Within the confines of this use case they are cheaper and more efficient per unit of cargo moved than cars or trucks.