Given the 500 square miles of Los Angeles and the 4 million people population, that's about a 60' by 60' plot of land per person. Given that doesn't include roads, highways, industrial or commercial zoning, and that people will group in housing (families), I think that's fairly dense for the type of housing which is currently in place, which is homes homes with yards.

It's not dense relative to other types of metro areas, but I think it's probably fairly dense for single level housing in an industrialized nation.

My point wasn't to imply that Southern California was very densely housed, but that there may not be a huge amount of unutilized land left to build high density housing one, at least not enough to really change the dynamics. And once the conversation shifts from just what to build and where to also who to displace to build it, it's an much harder conversation.

I could be entirely wrong, I don't live in LA, but my impression every time I visit is that there's not a lot of unused land, even if the land that is used isn't used efficiently (population density wise). If that's true, it's not just a NIMBY situation (even if it might have traditionally been one), as it's also a "don't displace historical group X that's been living in this area for decades" situation (whether entirely accurate or not).

We have not been limited to single story buildings for thousands of years. Saying this is the kind of housing currently in place really is irrelevant, because that argument would apply to farming communities etc. Instead High density means something and nowhere in California applies which is why housing is expensive.

PS: It’s a question of underutilization, where it would be economically profitable to take each of these buildings down and replace them with more useful structures.

As efficient as it may be, demolishing homes is about as bad an image as you could project. Few with political ambition would touch it with a pole.

Demolish the parking.

Whwn the vikings settled Dublin they set up some huts along the river.

Therefore the riverfront should be low density huts forever I guess.

That has little to do with what I'm saying. I'm not saying development shouldn't happen, I'm saying it won't on any quick timescale because of the existing infrastructure and how people fight to avoid change. All I'm saying is that rezoning to allow different building types won't lead to enough new housing immediately starting, nor even the change a decade from now being sufficient. A lot of things are required to fix the problem, and new zoning is just one of them.