Buildings are inspected in stages. So there is an inspection after the foundation, and then at a couple other points (I should know, my son-in-law is a building inspector). If one can build an entire home in 48 hours, there isn't much time to stop building and wait on an inspector to come out for the foundation, the walls, the wiring, the plumbing and whatever else. I guess inspectors could just be on site during the whole build, but that comes with a cost. It turns out it is 24 hours and not 48.
This is the guy in this case, but there are many more using other approaches trying to build buildings with robots. Some are trying swarm robots.