Every high speed rail in history has come in way over budget

I'm gonna have to go digging through some stuff to see if I can find a source but I'm pretty sure that's not the case (even if you ignore authoritarian style countries like China). California government is fairly dysfunctional and that makes things more expensive, and I say this as a proponent of CAHSR.

The biggest problem with CAHSR though is that the rich suburban fucks (especially on the SF peninsula) are trying to kill HSR with death from a thousand paper cuts^W^W lawsuits. That's how you get things like cities (coughathertoncoughbelmontcough) wanting underground sections built on someone else's dime. They'll cite things like noise while ignoring that a.) electric trains are quieter than diesels and b.) grade separation eliminates the need to sound the horn.

It's a really nasty self-fulfilling prophecy.