> If cities have become more dangerous in recent years, people will notice and change their behavior.
Dubious.
Certainly, behavior is driven by perception of danger, but whether perception of danger generally tracks with actual danger or not is…less certain.
I know for child abduction and child assaults by those outside of the family that has historically not been the case; and perceived danger has increased as media focus increased despite decreasing actual danger, for several decades in a row.
I don’t see why similar (or opposite, if media focussed shifted away while actual danger increased) trends would occur with other forms of danger.