Turns out it wasn’t just random street crime. It was being run by organised crime networks, and it went down significantly after they managed to disrupt a few major rings.
These waves do happen from time to time when criminal networks discover a new tactic, before the police figure out an effective method to deal with it. It was youth stabbings a few years ago and acid attacks before that, both are much reduced now.
Those criminals will move onto something else now, undoubtedly. Perhaps shoplifting, which it’s now reported is being also increasingly run by gangs. Point is, you can’t necessarily look at an individual type of crime as an indicator of criminality as a whole, could just be exploiting an opportunity.