Having driven both, heck even in England on the wrong side of the road.
I agree with the test they are faster if people can navigate them. However, i find people are more scared than dumb. Even in the UK where people are used to them if you get stuck behind and elderly driver that is too scared to hit the skinny pedal you will be stuck there forever, guaranteed. The 4-way stop gives them the comfort of knowing they have right of way at some point.
the 2 lane ones are weird but you get used to them and are pretty darn efficient.