I don’t think that is the only thing that is keeping this slow and expensive. I think the first estimates were way to optimistic (especially in terms of costs and funding opportunities).

I think the main thing that has been slowing things down is severe lack of funding, both from the state of California, and especially from the federal government. This is probably due to the fact that there was a lack of experience (both from the rail authority and especially from the legislator). Thankfully it looks like they have stopped withholding funds and at this point they have gained some experience. I doubt there will be another doubling of cost estimate nor much more delays (perhaps a year or two more at most).