From my PRR NY-Chicago timetable:
New York - Chicago was $58.20 for a compartment (bedroom?), equivalent to $1,032.50 in today's money. Plus, you would have to pay extra for meals, even if they were a lot better than flex. And that was during the height of the Depression, when I'm sure business travel was down.
I think there's a limit to my complaints about that $497 ticket I bought on the Lake Shore Limited a couple of years ago.
The main problem with Amtrak long distance service is they can't run the trains reliably and on time. I don't think that was as big a problem on the PRR of yore, the "standard railroad of the world."