[Zeke]

"....all the new ones are in residential neighborhoods where the posted highest speed is 30 MPH." There are no roundabouts on any boulevards.

Not one is a 4 lane street. Not one is on a street wide enough to have a median. Still think these are great? Most are on streets that are 40 to 50 feet wide.

There is ONE roundabout in the whole of Los Angeles and it's nestled under 2 freeways nowhere near residential.
Google Maps: 34.08125041693894, -118.2300230786747

Look at this one: 33.76618139773021, -118.1373864631611 Follow that street left and right to find 4 of these little things. Residential speed limit is 25. OH, and each one still has a stop sign. 4 way and 2 way.