Over the last year I've been flagging, + submitting to the business redressal form, a particular brand that has about 20+ spam listings in and around Toronto; most of their locations are at residential addresses but some of their locations are using the same address as their billboards, where there is no discernable way for customers to access/enter the property, much less a business-front - one spot is legitimately an empty lot with nothing but a billboard
Somehow we were even able to get it escalated it to where we had a Google support rep. actually responding but at the end of the email chain they said they had reviewed/escalated it as high as it can go but they did not find any violations for any of the locations we submitted - that was even with several pages/screenshots/links of evidence suggesting otherwise.
Since then, we've found several more brands using the same tactic but not at the same volume just yet - I know most high-density population areas have some level of listing spam but I haven't been able to find a clear answer as to why Toronto in particular seems to be such a hot-zone.