This news is distorting some facts. In history, there were entire subway systems built in California serving smaller metropolitan corridors of about 15 miles that were built for 6 billion USD and are operating well. According to the news article, the project cost would be estimated over 43 billion USD for the entire line, which would ultimately cover over 400 miles. The early cost estimates typically do not include environmental review and engineering design. When environmental reviews are completed, mitigation measures are defined and detailed engineering is done, of course the cost estimate will be adjusted up or down.

Apparently the news article is either misquoting or quoting people that do not understand how much things cost from one scale to the next or from engineering design to construction. So how can you believe that the project has a cost overrun when the project isn't even under construction yet?