With the exception of decorative 1-lane roundabouts in sleepy residential neighborhoods, all the roundabouts I encounter in Central and Southern California are

With the exception of decorative 1-lane roundabouts in sleepy residential neighborhoods, all the roundabouts I encounter in Central and Southern California are 2-3 lane circles with various lane->exit mappings, some of which overlap and some of which are exclusive. Drivers coming into them, who want to actually benefit from the roundabout and not just turn it into an awkward stop sign, are responsible for reversing the exit to lane mapping, then timing their approach to the intersection with an opening that will let them reach to their lane while maintaining a flow. If they can't manage to do that, of course they're supposed to stop and yield until an appropriate opening becomes available. Inevitably, the designated pedestrian crosswalk is some 5-10+ feet prior to where the car would have to stop if it does need to yield while awaiting an opening. Compared to a signaled intersection or a 2/4-way stop, where the pedestrian crossing coincides with a natural traffic stop, this basically means that approximately zero cars actually stop for pedestrians. Some are too busy to notice and others just don't want to have to deal with a stop and so ignore their responsibility. I assume you must live somewhere else, where roundabouts are smaller and play some different role than here.