This is not an American invention, nor is it interchangeable with a roundabout.
The main priority of roundabouts is safe traffic flow for cars, but they can (sometimes) still be very hostile to pedestrians. This type of intersection is meant to prioritize pedestrians as much as possible. The narrow street slows vehicles, and the sidewalk bump outs make people trying to cross the street extra visible and minimize the time they need to be vulnerable in the middle of the road.
Which isn’t to say that roundabouts are necessarily bad, they just serve different purposes
This is not an American invention, nor is it interchangeable with a roundabout.
The main priority of roundabouts is safe traffic flow for cars, but they can (sometimes) still be very hostile to pedestrians. This type of intersection is meant to prioritize pedestrians as much as possible. The narrow street slows vehicles, and the sidewalk bump outs make people trying to cross the street extra visible and minimize the time they need to be vulnerable in the middle of the road.
Which isn’t to say that roundabouts are necessarily bad, they just serve different purposes