I don't think this is an issue of engineer competency. If you gave it to a French company, even they would be bogged down by the US regulatory agency and simply fail.
I am a Czech, so no dog in this particular fight barks for me.
But the French train company SNCF abandoned the Californian high-speed rail project, citing local political dysfunctionality and comparing it unfavorably to ... Morocco.
Made perfect sense. Uncomfortable length to drive, and end to end trip time would be shorter (and more comfy) on a highspeed train than on a plane (getting to the airport early, security, baggage collection, taxi to the city, etc).
Like any transportation projects it won't make economic sense if you ignore wider societal impacts. Highway expansion or airport expansion would neither ever make any economic sense at all if you'd apply the same narrow model. Now if you include climate impacts and the true cost of the climate catastrophe HSR is really the only transit project on this corridor that does make sense.
Oooooh buddy, you mustn't be familiar with some layers French bureaucracy.
Imagine a unionized DMV.