This is a good video about a real housing development (ie. not just a single demo house) that explains a lot of those infrastructure details: https://youtu.be/Y-4S7cdo3tY
The thing is a conventional framed walls go up just as fast, all the other finishing in both styles of building is where all the time is spent. In that video they still are using conventional trusses as well. If you have ever driven by a building site after the foundation is poured and dried. Then drive by in the next day or two often you see pretty much all the walls are framed and standing sometimes even have all their sheathing on the walls. It's the finish work and all the small details where all the time is spent.
When I look at robotics transformers like RT-1 I'm left scratching my head why nobody has tried to build a robot to apply grout/plaster. At some point robotics transformers will be so good that they could learn directly from human demonstrations.