On your second point, I think a few different things are being conflated here. Usually setback rules require empty land between the building and the sidewalk, so they don’t serve to create any buffer between pedestrians and vehicles.
Also, some cities have streets with no setback and no sidewalk, where vehicle through traffic is generally banned. You could debate whether this is a good idea. Personally, I found having the entire street for pedestrian traffic, while occasionally stepping out of the way of a vehicle traveling at a few mph was more comfortable than walking along the sidewalk with vehicles traveling at 30 mph a short distance away.