Remember also that existing transit links are beyond fully saturated. It’s not really possible for people to switch to transit en masse before the decades it takes us to build bus terminals and train tunnels have elapsed. No public transit system has the slack to absorb the Bay Bridge drive-alone traffic, let alone 101 or 280. People physically won’t fit into the vehicles. There are decade-scale projects to address that, and I support them, but I don’t expect to see their fruits during my working life. Anyone working now is going to be retired by the time a second Transbay Tube starts passenger service, assuming we vote to fund it right now.
Here  is an article to covers parts of this exact subject.
Instead, we got a less-safe, grandiose art piece for over $8 billion. $400 million more if you want a bike lane.
What makes you think European engineering companies are any better? Europe is just as littered with failed, bloated, late and vastly over budget infrastructure projects. Hell the small bridge down the road from my office was supposed to be closed for 4 month for some maintenance work, it's now been closed for 14 month and there is still no estimate for when it will be done.
The New York City subway was built in the era of Boss Tweed