The narrowest street in San Francisco is roughly a regular European street. This[1] is par for the course on most European cities, while San Francisco has very few streets narrower than this[2] (and the average is probably wider, if you look anywhere westwards of Park Presidio where theoretically two way streets are wide enough for traffic to continue flowing in both direction even with double parked trucks.

I would also point out that I'd prefer narrower streets in SF[3].

[1]: https://www.dreamstime.com/stock-photo-narrow-san-francisco-...

[2]: https://www.google.com/maps/@37.7998615,-122.4141133,3a,75y,...

[3]: https://www.theguardian.com/cities/2015/may/08/san-francisco...