"and walking is made more viable at the stroke of a pen simply by changing the zoning and building code to actually allow people to build walkable neighbourhoods with retail amenities,..."

This is an easy claim but unrealistic in North America. For the Boomers that have lived in single family housing for decades, those who also represent the larget voting block in most major cities, you're expecting them to forfeit their percieved "quality of life."

Have you seen large apartment projects in US cities, they are atrociously designed, with the vanity of walkability but rarely deliver the NYC or San Francisco level of walkability that they are selling.

Yimbys would do well to insist upon better replacement products.