Regarding crime. A huge factor in that is "eyes on the street." Car friendly streets massively reduce the eyes on the street for two reasons:

1. Cars travel fast and they obstruct the occupants' view in all kinds of directions. So the cars themselves don't really count as eyes on the street in the same way a pedestrian would.

2. Streets designed for cars are less pleasant to be in as a pedestrian or cyclist, so fewer people will be out on the street. You only walk on those streets if you absolutely have to be there.

Look at some YouTube videos of "open streets" in New York during covid.