> We have fantastic technology in many aspects of life, but housing seems practically unchanged. I mean, buildings are constructed by teams of men placing pieces of wood by hand.

That's simply not true. The kind of high-intensity housing he is talking about is built by arranging large pre-fab pieces on steel frame. In modern tower buildings, the pre-fab pieces are built on an assembly line and actually finished and furnished before bringing them on site and placing them on buildings. It's a much more efficient industry than concrete jet printers ever could be.