Civilizations, human settlements, people's homes and communities aren't fungible commodity widgets solvable and movable through copy-paste solutions like technical challenges, no matter how much HN insists every world challenge from housing to world peace, is as easily solvable as those at their tech jobs.
Just because you can 1:1 reverse engineer a bomb design and have it work the same, doesn't mean you can just take a housing policy that worked in the demographic, geographical, historical and cultural context of one country and just drop it in another country with a completely different context and background, and expect it to just work the same.
This is the tech equivalent of: "well, it was working on my machine".