More like they're seeing what they can build with as little money as possible.
European high-speed trains routinely use existing tracks in urban areas, so what the CHSRA wants to do is rather routine in Europe.
Looking over the world, high-speed-rail progress has been very patchy and spastic, something which suggests political whim. This is likely because of the high capital cost of HSR lines, meaning that it likely takes a lot of political will to round up the necessary amounts of money.
But nonetheless, progress has been remarkable. France, Spain, Italy, Japan, South Korea, Taiwan, and China now have systems that span much of their nations, with more on the way. Germany is much more patchy, and the UK and Australia have done hardly anything.
Most US HSR is likely to be incremental improvements, and rather patchy ones at that. North Carolina, Michigan, Illinois, and Washington State have been going ahead with lots of improvements, even if that cannot be said of some of their neighboring states. The fate of would-be systems in Wisconsin, Ohio, and Florida also suggests political whim.
Turning from intercity HSR to urban rail, one finds the same problem of capital cost, and one finds the same sort of patchy development. Political whim seems evident here also. At least the US, some cities may start building urban-rail systems years ahead of some neighboring similar cities. For rapid-transit and light-rail systems primarily for urban areas:
San Diego: 1981, Los Angeles: 1990
San Francisco: old, San Jose, Sacramento: 1987, Oakland: none
Portland, OR: 1986, Seattle: 2009
Pittsburgh, Cleveland: old, Cincinnati: under construction, Columbus, Detroit: none
St. Louis: 1986, Kansas City: none
Philadelphia: old, DC: 1976, Baltimore: 1983
Houston: 2004, Dallas: 1996, (Austin: 2010)
Miami: 1984, Tampa, Orlando, Jacksonville: none