In UK and other countries where police are generally not armed, using a dangerous weapon often also adds substantial amounts of time to potential sentences, and there's either low levels of private ownership of guns (UK) or tight controls on storage and use (e.g. Norway has tons of firearms, but the law requires it to be separate into at least two non-functional parts that must be kept locked down separately, so your hunting rifle is not something you'll go fetch on a whim when you hear a weird sound), and so criminals know that not only are they unlikely to face an armed response if they don't arm themselves, but they're also likely to get off lighter if caught without weapons, and so there's very little incentive for criminals to arm themselves in most situations.
It's one of those things where de-escalation is nearly impossible because of the likely public response to news of dead cops, and how widely guns permeate the culture.