I think this is a pertinent point to the way roundabouts are implemented and used in North America. Cars are almost always going too fast on their exit from the roundabout, which renders the "yield" sign on the exit side crosswalks defunct. Not to mention that if they do yield to a pedestrian there, the crosswalks are close enough to the roundabout that they might be impeding traffic in the roundabout itself.

The crosswalks in the roundabout need to be moved away from the circle itself significantly (10-15m at least) for roundabouts to be safe for cyclists and pedestrians. At least for the way they are used in North America IME.

It depends a lot on the country you are in. In the Netherlands pedestrians and cyclists normally get priority, because the car is making a right turn while the other groups are continuing in a straight fashion. What probably also helps is that when a car is involved in an accident with a pedestrian/cyclist the default assumption is that the car driver is guilty.