This is a great reply. Thank you for engaging instead of just dismissing me or downvoting.
I want to say I agree somewhat: regulatory environments, complex zoning and permissioning, leads to development overhead and ultimately higher prices for everyone. (Ironically I seem to be getting pushback from fiscal conservatives in these threads even though I think we mostly agree there.)
Where I disagree is from this point right here:
> you’d get affordable housing without directly incentivizing developers at all.
You'd get it somewhere. Not necessarily in the cities themselves, because the law of supply and demand is still going to outstrip however much you liberate the ability to build. Cities naturally become unaffordable. They concentrate wealth and economic output and then grow in value because there are not unlimited lots that are equally central to this concentration.
This means that affordability, particularly in the case of cities (like LA), which is the thrust of the upzoning argument, is not actually addressed merely by the removal of impediments to building or changing zoning. The economic regime cities build guarantees the displacement of middleclass dwellings over time. Eventually you reach a point at which all the hairdressers and school teachers no longer have a reasonable commute. The city eats itself in its ever-spiraling productivity.
When you have a large, high-traffic, high-output geographic area (like LA), you have to think more creatively about how to usurp market dynamics inside of that area. That requires below market-rate mandates, as far as I can see. The invisible handle of the market will not settle this because the affordable regions are naturally pushed outward over time.
In otherwords, I disagree with the premise of most of these comments: upzoning is not the final word, not even, in the majority, the most important word for affordability inside of cities. California as a whole will benefit from upzoning. The actual city of LA will not see pricing regress because, as you noted, there are actually many more barriers to building in terms of building codes, etc. and because of the realities I mention in my reply.