The Key System is one notable example:
https://en.wikipedia.org/wiki/Key_System
The new Bay Bridge span was specifically not designed to carry rail, so rail over the bridge is not coming back.
I tend to think these are further away than most people think. But I also have a lot of trouble seeing how they don't massively increase traffic. Maybe you need less parking and maybe inter-car communications can make traffic move more smoothly. But does anyone seriously believe that people will drive less when they effectively have a personal driver at their beck and call?
No it isn't. Many neighborhoods are quiet and/or cheap because they're difficult to access. Their residents have a vested interest in keeping it that way. You don't vote for a new subway stop if you'll be priced out or have your perception fo quiet and safety ruined by the people it brings.
Everybody builds the infrastructure that the then-state-of-the-art calls for. That was roads and freeways for most of the US. It's an accident of history, not an idiotic mistake. Not doing anything about it for the past ten years is the possible mistake, but from the perspective of the people who already live somewhere, and like having relatively lower density, they have just as much right to doing things how they want as the new tech crowd interlopers do.