China has also spent the last two decades creating labor, supply chain, and other infrastructure for getting HSR built. California is basically starting from zero.

You also have to understand that building ANY infrastructure in the US is an exercise in digging a hole and screaming into it. Rich people who don’t want to be bothered by public works projects exploit the fuck out of CEQA to create delays and cost overruns; it seems that the US has a lot more local authority compared to other countries, which means that counties and municipalities and local NIMBYs have a lot more room to removed, moan, and stonewall, and must be parleyed with; the US also depends very heavily on private contractors to get infra built, which ends up being really expensive before you start accounting for bad actors that exploit the bidding system. On top of all that, there’s one other thing that must be screamed every time this comes up: highway and interstate projects in the US nearly always go over budget, and there’s at least one I’m aware of in the northeast that is wildly, insanely over budget to a similar extent as CAHSR, but you don’t see anyone removed about that. The people who want to sell you shit don’t want you to have any choice but to buy their shit. It’s not going to be easy getting away from the US’ car-only model, but it’s doable and worth doing.