Comment by kjkjadksj

Because retrofitting them properly requires emminent domain. The ones they shoehorn onto former four way stops are so useless. They are so tight you still have to face a stop sign vs being able to just seamlessly zipper merge in a proper larger circumference roundabout. When they have room to build out a proper roundabout they are usually OK but that is hard to do outside say new suburban construction due to lack of available land on the right of way.