FWIW the issue is not mostly the builders—the issue is contracting practices and program management/oversight. California HSR hired (among other contractors) Dragados, which has a long history of building huge amounts of HSR in Spain at some of the world’s lowest costs. Look how that’s gone.
Nor is the problem “bureaucracy” as a sibling comment said—actually the opposite is true, we need more “bureaucrats” with technical expertise to oversee contractors so the taxpayers don’t get our lunch eaten. We have gutted all technical expertise from government and now we often outsource the oversight to even more contractors (sometimes the same ones doing the designing and building!). Results are predictable.
We also have a huge problem with litigation and “regulation by litigation” as a replacement for actual “bureaucratic” oversight. Agencies conduct insanely expensive years-long public feedback programs and environmental studies (never mind that electric rail is innately good for the environment) for fear of lawsuits, which happen anyway and delay things even more. Instead of regulation by litigation, the government should step up and provide a clear set of achievable regulations, and if agencies/companies meet them, they can start building.
The countries that do rail infrastructure really well and really cheaply are not always the ones you expect—some are stereotyped as lazy and bureaucratic (Italy, Spain) and some are thought to be places where everything is expensive (Switzerland, Norway). We have a lot to learn, but often we tell ourselves that it just can’t apply to us because we’re so exceptional.
For details on the specific problems and solutions: https://transitcosts.com/