Sadly, the biggest obstacle to housing in most communities is zoning. Most communities have strict zoning laws that force out affordable options.
Financial formulas also work against the creation of affordable housing. The financial formulas prevent banks from giving loans to affordable houses on expensive land.
The technology of building has advanced to a point where it is possible to put more and more people into affordable homes. Unfortunately, the financial and political structures of the world seem to preclude such options.
RE: 3D Printing A Solution To Housing Affordability