I think the article is targeting more arterial streets that have 12-foot lanes (e.g. one-way, two lane streets). Not highways running through cities, which are not "streets".
From my experience, few cities have four lane highways running through them - and if they do, they are grade-separated from pedestrians. In cities where the four lane highways are at grade with sidewalks along them, this is a different case. Those roads are hopeless and should be subject to complete removal.
In my experience (limited mostly to Gainesville) a lot of fairly residential streets in Florida with speed limit ~30mph are ridiculously wide, often 3 or 4 lanes each way.
From my experience, few cities have four lane highways running through them - and if they do, they are grade-separated from pedestrians. In cities where the four lane highways are at grade with sidewalks along them, this is a different case. Those roads are hopeless and should be subject to complete removal.