You would think it would work on transcontinental flights in the US.
747s operating just one or two frequencies per day between East and
West coast city pairs at rock bottom prices.

World Airways used to do that JFK-LAX. Didn't last.

If you look at the number of flights on that route, on planes ranging
from 737s and 319s to 767s, at this point you'd have to expect that
everyone else would match your fares and keep you from filling up your
plane, even if they were selling below cost. It's the airline
tradition.