[CalRobert]

They are a thing, I had one built. But dealing with meddling biddies in the local council who wanted to tell me what my house should look like (not to mention that the only real house is one made of crumbling concrete blocks) put up a lot of barriers.

Example: https://www.palmatin.com/

I honestly think a lot of the problem comes down to having people in positions of power who view affordable, commoditized housing as a threat.