And there is a driver problem, majority of American almost never have any experience driving on roundabouts. I seen some would simply cut off the roundabout traffic and proceed on their way without yielding.
https://www.google.com/maps/@56.5903811,-3.3375594,3a,75y,21...
- If you have one 'entrance' to the roundabout which is partially busy, say at rush hour, it becomes near impossible to enter the roundabout from a different direction. With a normal roundabout many more cars can be on the roundabout at once and a natural flow, even from less used entrances, just happened. This does not work on a mini roundabout.
- Where they have replaced a T junction, people often ignore it causing (near) accidents when going "straight on" when they don't have right of way.
They are definitely not a one size fits all solution.
The data shows that roundabouts are safer and even improve traffic flow. But they're also a nightmare to install after the fact, which is why it is so uncommon. All we can do is stop making the same mistakes going forward.
Same thing with burying power lines: Far cheaper to do with new construction, substantially more reliable and better able to withstand natural disasters, but we aren't. Society is just bad at planning for tomorrow if it costs us a little today at every level.
You are also required to have your lights on when you are driving. It notably increases visibility even during the day.
I came back to the US really wishing those policies would go into effect nationwide.
Having said that a lot of roads in my area are already built around 4 way stops and it's not easy to undo that, but new construction in my area of suburbia US has adopted the roundabout.