Someone made the argument that in the US our rails were built by men half killing themselves for low wages and with very few safety standards. That means a modern buildout is much more expensive than it was historically and the political will to build that budget is difficult or impossible.

Hyperloop is a run around that problem. Largely autonomous/low staffed boring that's non-union labor, non-public sector can make a lot of progress quickly. There's no public sector union demanding x amount of jobs, x amount of pensions, and other expensive regulations or union concessions. Musk's Boring Company thinks it can build tunnels for a fraction of the cost privately without much public sector regulatory weight and they might be right.

HSR is the saner idea, but without Congress funding it, its just not going to happen. Obama made a big push for it during the stimulus but more conservative states decided against accepting the money for both ideological and financial reasons. Once enough states say no, then the rail can't go very far, and the project eventually died:

First, Tea Party conservatives in Florida and wealthy liberal suburbanites in the Bay Area began questioning their states’ plans. Then, just as Joe Biden was calling for $53 billion in high-speed-rail spending over the next six years, a crop of freshly elected Republican governors turned down billions in federal money for lines in Wisconsin, Ohio, and Florida. Finally, Republicans in Congress zeroed out the federal high-speed rail budget last month.

http://www.slate.com/articles/technology/technocracy/2011/12...

It'll be more like 3 hours, and it will end up costing around $100 billion. It would be dramatically cheaper and faster to subsidize free plane tickets between LA and SF for the next 50 years.

HSR works well in places with high density and competent infrastructure construction strategies. California has neither.