What that leaves your argument with is that existing rail only makes things harder because of a sunk cost facility. Let's improve our bean counting then.
Maybe America is one big sunk cost fallicy, being an older republic. Time for some creative destruction I guess.
those parts of Europe, let's not forget, were rather thoroughly flattened to a wet paste about 80 years ago, and were rebuilt with nice, straight, quick rail lines by people who knew how fast trains that weren't built in 1840 could go.
The U.S. has essentially stopped building urban interstates since the late 70's, when opposition from residents became too strong to ignore. I don't foresee this changing in the near future.
My understanding is that construction costs in Europe are rising as well due to (among other things) increased use of tunnels in urban area due to opposition from residents.
I know the popular Western image of infrastructure development in China is jackbooted thugs forcing farmers off their land, and there's some of that as well, but most people are reasonably happy with the compensation they get. The Shanghai-Hangzhou maglev project (below) is also an instructive case study of an ambitious rail project that was cancelled largely thanks to (sadly unwarranted) public concern.
https://en.wikipedia.org/wiki/Shanghai%E2%80%93Hangzhou_magl...