>>1909311because the purpose of HSR in the 21st century is to compete with air travel. Airplanes can already travel at over 500 mph, so if you intend to do anything intercity, you need state of the art HSR in the style of Shinkansen or TGV with dedicated and separated corridors.
The two main advantages HSR have over air travel is that 1) you can bring the trains into the heart of the city or close to it with relative ease, and 2) the security checks are not as severe, especially if you are not traveling international (which would not be the case in most proposed corridors), and you can basically arrive at a station 5 minutes before departure. But these advantages are diminished quickly when you don't use state of the art technology, for example a 100mph trip between LA and SF would still take around four hours, and that's not including other possible stopls such as Bakersfield or Fresno, two larger cities between the two major urban regions of California
