Another thing that often plays into this is access for firefighting apparatus. A lot of modern streets in North America are designed to be wide enough that two

Another thing that often plays into this is access for firefighting apparatus. A lot of modern streets in North America are designed to be wide enough that two fire trucks can pass each other. But North American fire trucks are huge (often around 8 feet/2.5 meters) and a 5+ meter road isn't really human-scaled. Part of this might be necessitated by the fact that we build most structures out of flammable materials, but with better fire-control technology (sprinklers) that could be mitigated. It's amazing how often alleys/laneways are some of the most treasured parts of a North American city.