Look at the route California's HSR takes [1]. That's a map drawn for short-term political gains, not long-term utility.
Unless we develop technology that cancels out inertia, that track is speed limited for much of its route. Comparing non-American infrastructure costs and benefits to American infrastructure is misguided because American infrastructure costs unreasonably more [2].
[1] http://www.ushsr.com/images/632_CA_HSR_Phasing_632.jpg
[2] https://www.nytimes.com/2017/12/28/nyregion/new-york-subway-...