Perceptions of crime waves are mostly driven by propaganda, not measurement.

In some cases, a "crime wave" doesn't represent an undifferentiated mass phenomenon, but rather the behavior of a single organized crime group: it's not that "everybody is being more criminal today" but rather "there is a specific gang that has figured out how to get away with a lot of crime". This seems to be the case for a lot of property crime in my part of the country.