Training is important, but the idea behind roundabouts is "we'll have plenty of collisions here, but all of them will be 30km/h or less".

Obviously you want to having bicycles or pedestrians in your roundabout so adding a bike/pedestrian path next to the roads has to be part of the plan if you want to do it right.

But you modulate speed and rotate the car while navigating the roundabout, which solves the constant speed/constant bearing problem. At a roundabout, blind spots are all over the place and will never perfectly track another traffic participant.