In Europe we have a lot of roundabouts that work the opposite way, priority is given to anyone inside/exiting the roundabout, which would seem easier to handle for automated systems.
Also in Europe it depends what road signs are at the roundabout. They have no special status in my country and can be looked as a "T" intersections connected to a circle. In most cases there is a yield sign for the cars approaching the roundabout so the cars already on it have right of the way, but it is not the case for all roundabouts. Also, some roundabout allow exit from the two rightmost lanes, others just from one—it also depends on signage.