> Inevitably you'll have to grandfather in existing infrastructure because a lot of it is from ancient times and all you'll do is make it impossible to have a Chinatown, or a NY brownstone. So what you'll get is that almost nothing new gets developed because the cost structure makes it impossible.

I don't see how that's true - if you create cities or neighborhoods which are more walkable, such as New York's Chinatown, then you'll have less civil liability than suburban car-centric infrastructure. I would think that NY style neighborhoods would be MORE incentivized