The urban rich and powerful can afford to live within short walks of their offices, or right next to stations on the best parts of (small) existing transit corridors. They are most assuredly not sitting in rush-hour traffic.

>low density, partly to accommodate cars

Figure 1000 people work downtown, half of them park in 200sqft spaces, the other half live in 400sqft apartments.

Convert all the parking to apartments. Now downtown can support only 750 workers. Great for me if I'm one of the 250 who no longer has to drive, but what if I'm one of the 250 who can now neither drive nor live there?

Statistically, it was worth ~$9,000/year to me not to ride a bicycle or use public transit. Unless that was purely ignorant, starting to do so will be a bad time.

>bad zoning laws,

I'm with you there. We need to massively increase the height of buildings in the small walkable cores and along transit corridors so that more people can live in them. Over time, employers could also spread out, so that there is not a single downtown that everyone's trying to get to. And of course it is ridiculous that any one lives far from a grocery store by fiat, rather than by economics.

>It's one where nobody owns a car, and everyone shares the benefits of that.

But if we do that and, the contention for housing along the transit corridors will be so intense that only the wealthiest can remain, even with free-for-all zoning and a huge construction boom. I've no doubt that the proposed new state of the world will be awesome for the few people who can afford it, I merely doubt that I will be one of them, and I'm not looking forward to 3+ hour/day commutes, no matter how safe the streets.

Sprawl, the automobile, and the highway are fundamentally housing affordability devices. Land value isn't so important if you can traverse 10 miles in 10 minutes. When 10 minutes its half a mile, it suddenly matters a great deal.