There are definitely uncontrolled intersections once you get out of the cities. My understanding is that if unmarked, there’s an implied give-way at the side road in a T-junction and all roads in a four-way junction.
Outside of cities on limited access highways seem like the much easier situation--and, frankly, a pretty significant win for both comfort and safety once people give up their dream of having a personal chauffeur for their entire lives. It's self-driving in e.g. Manhattan or Boston that I can't really begin to imagine in less than decades.