Earlier quoted context omitted.
For a lot of trips, Amtrak is about the same as flying. Looking at a round trip from NYC to Chicago, on the arbitrary dates of March 26 to April 9, Amtrak costs $180 while Kayak shows the cheapest flights at $159. Of course, Amtrak takes much longer (20 hours) but is less hassle, and at that price the flight only lets you take one carry-on while Amtrak lets you bring two checked bags and two carry-ons. Adding checked…
NYC to Chicago probably has a decent customer base to support that price point. For amusement, try Miami/Seattle via Amtrak. It's possible, since I looked up the route [1]. One week transit time one way, at $2,000 (I don't recall if the price was round trip or just one way). And trying to work on the train was fun (too "swishy" to use the computer: http://boston.conman.org/2015/08/05.2 ). Totally not worth it for me.…
(But maintaining the track to this quality would be even more expensive if there was as much freight on it as tracks in the USA carry.)