The theory says that new units are added when prices are high and building new units is practical. Building new units is inhibited, therefore prices go up, exactly according to the theory.

The problem isn't the theory, it's the inhibiting of adding more units.

There's been an assertion of a "body of literature" but no pointers to it, no assessment of the data quality, no assessment of the validity of the interpretations, etc.

There are entire bodies of literature based on zero evidence, due to epistemic doubt about evidence as grounds. For example, critical geography actively rejects basing their body of literature on evidence, and reaches conclusions about gentrification and displacement and housing production that are quite contrary to both the evidence and standard economic theory. Yet the work of critical geographers is endemic in public policy around urban planning and political debates on housing production in urban areas.

I would agree in general that theory must change to match the evidence, but again, what evidence is at play in any of this thread?

The existing price is high not because it should cost that much to create a new unit. It's because you're only allowed to put one unit on a particular plot of land, which makes the land cost per unit 10x as high as building 10 units there. Adding more units doesn't require you to use lower quality materials or similar, it just requires you to actually build them.

This is trivial to empirically disprove. Look at the listings for similar units in an arbitrary city. Are they all exactly the same price? No, and then the landlord who offers the lower price for an otherwise equivalent unit fills their vacancy sooner.

> They raise rents in lockstep and then offer "specials" like a month off (amortized) that lower initial out-of-pocket costs without affecting the base rent, which gets raised on subsequent lease renewals to make up the difference.

These are obviously gimmicks, but who is requiring you to fall for them? If you're planning to stay somewhere for a long time then look at the base rent and the length of the lease. Let the landlords offering "specials" and short lease terms get taken advantage of by the tenants who know they're going to be moving in a year anyway.

> The only option to avoid this is moving every year (instability being clearly great for community /s) since corporate landlords will not negotiate rates.

An obvious option to avoid this is to avoid corporate landlords. Most rental properties are owned by a "corporation" in the sense that it's an LLC for liability reasons, but that doesn't mean the ones owned by an individual who lives in the same city and has fewer units than you can count on one hand behave the same way as the ones owned by some private equity schmucks, and there are lots of the former.

Also, who wants to rent the same unit for 30 years? Renting should be for people who haven't saved a down payment yet and people who are planning to move soon. When we're seeing people in middle age who want to stay in the same place but still can't afford to buy anything there, we need to be doing something about the unaffordability of buying rather than accepting the premise that we're going to continue screwing them into needing to rent.

The zoning restrictions cause the higher rents by themselves. No collusion is required and no solution is possible without addressing that.

Whereas if you do address that then how is the collusion supposed to work?