Maybe you just knew more cops? At one time that often seemed to be the way to spot an off duty cop was a civilian dressed Crown Vic that probably parked at home next to the work provided Crown Vic. Though I also knew someone that bought used cars solely from cop auctions partly because they weirdly liked the "harshly restored to civilian use after several years of work abuse" aesthetic about a former cop Crown Vic and also supposedly because they were incredibly cheap at auction if you didn't mind being a lifetime mechanic because those cars were in awful shape coming out of the auction.