The rampant auto thefts and breakins/thefts from vehicles/houses in my area lately haven't really needed scanners given the great distances police have to travel (my RCMP detachment is enormous and I'm basically at the far end of it). Locals are trying to change that with some citizen patrols and etc., plus greater surveillance both electronically and biologically (i.e. eyes and ears). That having been said, for the current spate of thefts/crime over the past 6-8 weeks, the region where every person who's been charged for these crimes is from, is legendary for literally every house (and I'm not being hyperbolic) having a scanner. RCMP exploit this when they are looking for someone and/or for help.
I can't really comment on whether or not scanners are in use by the criminal element here. Some of you say they are, though they don't seem to get mentioned when these people are arrested - although in all fairness RCMP aren't really publishing a catalog of all items seized when arrests are made, so I wouldn't know for sure. Realistically I'd like to think that if all these clowns had scanners, they wouldn't be getting caught as easily as they are, but as the saying goes - they're not exactly the brightest bulbs.