I’m all for rail when it makes sense. China is lucky in the sense that their timing was good for HSR. They had the capital, the right available technology and the population density to support such a system. However, for the large majority of Chinese, the rail is very expensive – it’s great for relatively wealthy city workers and foreigners.
The CA HSR between LA and SF is a colossal waste of money – if it is ever completed, it would be a huge financial drain on CA state resources. The only way it will be economically feasible is when a new technology system is fully developed (Hyperloop). Yes, most roads are funded via sales tax, and so could the HSR, but the ridership data behind it is overly optimistic. People are just not going to pay the prices on the rail, especially with a 3 or more people – It’ll be cheaper to drive.
CA is better off spending the money on regional rail and intermodal transport. Such as SF-Stockton/Sacramento/Fresno. LA-SD/Bakersfield/Palmdale/LV. Why? Because commuters will use these routes every day as opposed to the once in a while travelers between LA and SF (and competing with air travel for the same passengers.)
I’m more optimistic on South Florida. The distances are way shorter, the population density substantially higher (for relative distance), and it’s regional.