Big problem with late game was/is that you had all your districts laid down already and the building game was basically done. Railroads (and canals and the other new stuff) were attempts to extend the building aspect of the game that most people really like further into the game. Problem is, rails are a pure movement feature, they don't actually do anything else for you. So, when you build them you likely don't really feel like you are achieving industrialization or something, which sort of makes them a very muted addition.
If they had some economic benefit or application, then players could potentially have another round of planning and building to improve their cities to keep them engaged in an exciting way. (One could even utilize the trading post system!)
As it is, i like the graphical change and I still try to build rails, but it lacks a real sense of achieving anything because they're only good for moving your troops around to go do an emergency or what have you. (I understand there's the niche case of international trade route benefits but that's not the most compelling thing most of the time.)
The fact that there is only incremental speed increase for unit movement and no economic/social/cultural benefit at all means that there are still no railroads in Civ VI. There are roads with funny cross-hatching, but they do not act like railroads, so they are not railroads.
Unit movement: a marching unit can average 15 - 20 miles a day for a long period, up to 30 miles a day for short 'bursts' which will end up, if continued for too long, with the men and the draft animals hauling the heavy weapons exhausted. A motorized unit in convoy, if it has ready supplies of fuel, a good road, and good traffic control (an often overlooked point) can average up to 200 miles a day - about a fourth of that if they are 'moving to contact' staying ready for battle (very few 'fast' exportations or movements in WWII actually exceeded an average of 50 miles a day in any circumstances).
A railroad train in the 19th century (Industrial Era) averaged 100 miles a day even on primitive single-track lines, up to 600 miles a day on multi-track lines with electronic signaling and train control in the late 20th century (Atomic Era)
To this day, the preferred method of moving tracked vehicles long distances over land is by rail: aside from the wear and tear on the tracks and vehicles, you haven't seen destruction until you've seen an asphalt road after a few hundred 25 - 60 ton tracked vehicles have ground over it (Disclosure: I was a tank driver Once Upon A Time, so this is not purely theoretical knowledge from historical studies!).
To replicate the effect of the railroad and not just the purty graphics, Civ VI would have to have the following:
1. City Radius no longer applies. The city can draw Amenity Resources and/or Food from any tile it is connected to by railroad.
2. Unit movement by rail is, comparatively, 5 to 10 times faster than any other ground movement. BUT, realistically (if we can use that word in Civ VI at all), railroad movement cannot be used within ZOC of any enemy ground unit, and enemy units cannot use your railroads for railroad movement.
3. Anything that has a 'radius of effect' extends dramatically further with railroads. Fresh oranges can be shipped from California to Chicago, Fresh Tea from west coast ports to New York City: 'radius' does not apply. The Factories of Pittsburgh or Detroit (or Essen, or Birmingham) can produce for anyone connected by railroad. People can (and did, and do) travel by rail 1000, 200, 3000 miles to visit Crater Lake or the Grand Canyon - or the Bolshoi Ballet, for that matter. This kind of 'people travel' for Amenities or Culure also, of course, extends to Air Travel, Aerodromes or Air Ports.
4. Railroad connections multiply the effect of other types of travel and some Districts. A Commercial Hub, for instance, that is also connected by rail will dramatically increase its effect on commerce, because the sheer volume of trade increases by orders of magnitude (one wagon or truck = 2 to 50 tons; one train = 600 - 10,000 tons moving 3 to 10 times faster and further). A port/Harbor connected by rail basically extends its trade benefits to the end of the railroad connection.
The Industrial Revolution was as much as Railroad Revolution as it was a Production Revolution, and from the effects also came Social, Cultural, and even Organizational Revolutions (all modern armies and most corporations resemble in basic respects the organization of the first large railroads: that's not accidental)
Until Civ VI at least attempts to model some of those effects, it has no railroads, just a road with funny graphics.
