Vienna's affordable real estate is entirely down to the quantity of housing they build - around 2/3 as many units as NYC with 1/4 the population. It has nothing to do with locking private capital out of real estate (which anyway isn't what Vienna does - there is private housing too). U.S. cities used to be affordable too, when they were building lots of housing.
You’re right, it is quantity. There is only so much housing that could be built in Ibiza, it’s only about 220 sq miles. If a majority of that housing was non market housing, this problem wouldn’t exist (and folks with wealth would simply fight and churn over the minority of market housing).
Non market housing isn’t exposed to capital, and therefore avoids the demands capital places on housing and extraction of ever increasing rents.
That argument is being made all the time, without sufficient evidence to back it up. Even places which have experienced tremendous growth of their housing stock have often seen massive house/rent increases (e.g. Melbourne).
Even more the theory can't explain the sudden jump of house prices that happened during covid in many places. People were moving out of the big cities and house prices still increased? How can that be caused by government regulation not building enough houses.
The reality is that the house prices are much better explained by the fact that the top 1% have essentially unlimited funds compared to everyone else and the main thing to buy are assets, especially during covid.
It's easy to observe when walking around the richest parts of cities like Melbourne, Auckland, Sydney... 90% of thr biggest houses are almost always completely shuttered, because it's the 5th home for the owners and they only use it for a couple of weeks a year.
Slow Boring frequently discusses academic studies and quantitative evidence around the relationship between housing supply and affordability, if you're actually interested.
But what really requires evidence is the extraordinary claim that housing is some kind of special case market where prices don't respond to supply, despite the fact that places with high supply elasticity (Texas, Tokyo, Vienna) are more affordable than places with tightly limited supply, and despite the fact that housing prices took off in the U.S. just as strict zoning became common.
Prices increased during covid because everyone was suddenly spending much more time at home and wanted more space, a home office, etc. This is well understood.
The top 1% have more money to buy everything, not just houses. But most other goods are getting more affordable over time, not less.
So where are the citations? Also you're acting like housing affordability is a US phenomenon. It's global and effects essentially all large cities worldwide, funny you mention Tokyo which has seen massive increases of housing prices compared to salaries [1]. Saying land/housing behaves like other goods completely ignores the fact that land/property is by default a limited supply asset that almost never depreciates in value, that is very different to pretty much any other good. People have shown that much of the increasing inequality highlighted e.g by Picketey is due to assets (largely land/housing)
https://www.slowboring.com/p/what-can-we-really-learn-about-...