japan also has tunnel infrastructure for cars. one of my most vivid memories of visiting there is driving in and out of many-miles-long tunnels, and coming out of the last one smack dab in the middle of kobe. it was magical.
you'll never get change if your goal is to make cars so inconvenient that it pisses off the overwhelming majority of voters. cars are here to stay, so let's accept that reality and work around it. what you can do is demonstrate a better version of the world that people can get behind. but yes, it's not to create more car infrastrastructure, but actually less, because tunnels are expensive, so we'd be more selective about where to put roads. then we can also strategically reduce street area dedicated solely to cars (particularly street parking, but also lane number and width), reclaiming much of our limited surface area for people first.
> "Then, the only vehicles using the streets are mostly taxis (they don't need parking) and trucks, not personal cars. Narrow streets + no parking lots means buildings are much closer together and the city is dense enough for walking and cycling (with the help of subways of course)."
yes, let's build denser/closer together, build trains/dedicated busways, and let's not build (surface) parking lots. that's not incompatible.
off of the underground roads, you can put central, underground parking to serve urban neighborhoods and eliminate the need for permanent street parking (obviously services could still have surface space for intermittent parking). you could have fun little green alleyways aboveground (like in japan!) to access the central parking lot. you could even use a single underground car alley under the middle of a primarily residential block to provide access to underground garages under homes/apartment buildings. imagine how cool it would be to replace the street between you and your neighbor and set up a sports field or a garden or a picnic area, or any number of possibilities (even a whole row of new housing could fit down most "residential streets" in many places).