I lived and drove in Italy for over six years and never had problems like I find in the US. How many automobile accidents do you remember seeing in Italy compared to the US? As for walled cities, IIRC, there are some cities that expressly forbid any automobile traffic while others allow them but only in designated areas. Soave, just east of Verona, comes to mind as one that allows vehicular traffic is certain areas.

Can you imagine the traffic jams if the Italians, or any European city, were to get rid of the traffic circles? Yes, at first they can be a challenge, but once you get the rhythm and flow of getting in and out it is a breeze. Of course, I have not tried the traffic circle around the Arc de Triomphe in Paris.