My first relationships with roundabouts came in Washington DC. I understand they were meant to confuse an invading army. They certainly do an effective job of confusing invading commuters.
Greensboro has recently added roundabouts in several locations, some downtown and some in the burbs. I actually saw one woman, stop, watch for a few minutes and then backup to the nearest place she could turn around. I don’t understand how a woman that can backup can be intimidated by a roundabout.
I remember reading actual original purpose was to serve as defensive points in DC. Look at a map of DC. Put a company of troops into spots like Logan Circle, Dupont Circle, etc, with cannons (or, later, machine guns), and you pretty much dominate movement within the DC area.