There are also a lot of rather substantial engineering issues that have to be overcome in California that the train in China didn't have to consider. For example, the high speed train in California also has to cross notoriously rugged mountain ranges. The Diablo Range has a smattering of two-lane roads winding through it because it's so difficult to build through the gnarled hills. In the south, the Sierra Pelona and Tehachapi ranges almost caused California to be split in two separate before some rather remarkable feats in roadbuilding connected the two halves of the state. As such, there is an immense amount of planning, engineering studies, etc that need to take place before construction can start.
Additionally, there's a huge political element. A vocal minority of people have done everything they can to try to keep the project from taking off for various reasons. As such, there have been a rather insane amount of lawsuits filed which divert money to lawyers and time that would better be served by actually putting shovels in the ground. There are people who want it to fail for the sake of failing, because they want to bang their "government doesn't work drum" to the detriment of the taxpayers who are stuck paying for lawyers to fight their silliness.
Additionally, there's a huge political element. A vocal minority of people have done everything they can to try to keep the project from taking off for various reasons. As such, there have been a rather insane amount of lawsuits filed which divert money to lawyers and time that would better be served by actually putting shovels in the ground. There are people who want it to fail for the sake of failing, because they want to bang their "government doesn't work drum" to the detriment of the taxpayers who are stuck paying for lawyers to fight their silliness.