You're missing the point ... you can't see much of interest at 35,000 feet in a airplane. Train travel allows travelers to see the country at ground level, much more interesting.
On the other hand, plane travel lets you go to where you want to go, and spend extended time at that destination, unlike the train where you have short stops.
If I have 10 days, I can spend 8 of them on the train across the country and back, or I can fly to Reno, spend a few days in the Northern California/Nevada area, fly to Denver, spend a few days there, fly to Chicago, spend a few days there, fly to New York, spend a few days there, then head back to San Francisco.
The train can be a fun trip, an enjoyable excursion. But it’s not a replacement for normal commutes and most travel in the US.
I didn’t write that.