Your paragraph about Naples is what terrifies the urban transportation community about self-driving cars. These vehicles will still have stopping distances affected by their weight and velocity. When vehicles move at 40 mph, pedestrians, bicyclists, scooter riders, children chasing after balls, transit users disembarking, etc. will still be in mortal danger unless the people never make a error. If history is a guide, the powers that be will react by prioritizing speed in vehicles over people on the street. This was the point of my piece back in 2016: https://medium.com/self-driving-cars/searching-for-the-city-in-the-self-driving-car-a879b78cc4a0
Policies to maximize speed on expressways and policies to decide the appropriate speed for urban streets and local roads are two completely different types of decisions. It pains me to see them presented as nearly equivalent.