A truck will drive up to the site with a stack of lumber on it. Workers will individual measure, cut, and fit the pieces together. Wiring is all eyeballed by the electrian, and custom fit. The same for plumbing. Finish carpentry is all done piece by piece, by skilled craftsmen, and all hand fitted (and are a huge component of the expense of a house).
It all seems ripe for a revolution.
I'm not suggesting that houses be all cookie-cutter identical. But a custom design could largely be built in a factory, trucked in, and then you'd just have final assembly done on site. The result would be higher quality and lower cost (and less labor).
You can see some of this with roof trusses today, which are custom built in a factory and then trucked to the site.