Gig 601XL Builder writes:

The USA isn't France. In 2005 the average airline passenger trip length was
866 miles. That's around 1393.7 km. So our average trip length is longer
than your faster cheaper target.

The principle revolves around the enormous extra time required to take the
plane. Trains go from city center to city center, and so about the only time
you spend on a train trip is time actually riding on the train. Airplanes, on
the other hand, have a built-in delay of two hours or so at both ends of the
trip, irrespective of time in the air. So a train trip that requires four
hours or less always wins over a plane trip, no matter what the distance
involved.

In general, I find that the threshold seems to be around 1000 km, which is a
bit under four hours at typical high-speed-rail speeds. If you run the trains
faster, this threshold rises; if you run them slower (for example at U.S.
speeds), it shrinks until it's no longer worth discussion.

A high-speed-train could connect Los Angeles and San Diego in about 40
minutes. This beats the 4 hours of plane travel by a handsome margin. It
doesn't matter whether it's the U.S. or Europe, the numbers work the same way.
The U.S. resists such ideas for reasons unconnected with the actual efficiency
and travel time.