Building technology actually has advanced at a really good pace and most construction has been significantly automated. Most homes and buildings go up amazingly fast due to a lot of prefab and modular designs as well as a lot of process mechanization. The guys you see on the construction site today are usually doing more assembling rather than "building."

The conceptual 3d printed type homes are interesting but they are limited in scope in that seismic and load issues require materials and configurations that are not per say printable. (In other words you would likely not want to live in a 3d printed home in SF).