Did Germany and Tokyo really get affordable housing through planning?
It doesn't appear so.
Not that long ago Germany as a whole featured heavily in this debate over planning rules and house prices. With Frankfurt topping the latest UBS real estate bubble index, and Munich at number four, we don’t hear much about that anymore.
Tokyo is another city where planning rules are argued to have led to cheap housing.
Have we all forgotten that Tokyo was the world’s most expensive city not that long ago and is famous for how small its dwellings are? It also has less than 50% homeownership.
Across the central 23 wards of Tokyo, there are only 19sqm of dwelling space per person. Only 22% of Tokyo households have more than 29sqm of space per person. Across the prefecture as a whole, there are about 30sqm per person of residential space.
Australia has about 90sqm of internal residential space per person—roughly three times as much as Tokyo. Australia would need to nearly triple its population without building a single extra dwelling to have the same "housing abundance" as greater Tokyo, and would still have way more private garden space.
Yes, there is an overall trend in Japan towards more dwelling space per person. But this is driven mostly by the rising number of elderly households, especially elderly singles. When an elderly couple remains in their home after their children leave they increase the floor space (and dwellings) per person even if that young adult child moves to an apartment with less space than their share of space at their parent’s home. When one person from an elderly couple dies, they leave behind an elderly single-person household, boosting the floor space per person metric (as well as dwellings per person). Many countries whose ageing populations are not as advanced as Japan’s will also see this same trend automatically.
Another issue is Japan’s long period of deflation. CPI is up 10% in Japan in the past three decades, while it’s up 300% in the US, for example. Average wages have also been flat for decades. It is not a good idea to compare rents or prices in Japan without factoring in their unique wage and consumer price conditions.
Overall I’m not persuaded that a housing market more like Tokyo’s is desirable. On the more substantial point that relaxing town planning rules got that outcome, I find little evidence.
fn  I’m wary of charts like the one below since the only statistics I know about dwelling sizes rely on self-reported estimates by various ad hoc surveys by statistical agencies.