I am not sure what you mean by Ordinary Traffic Stop. Ordinary traffic stops don't involve guns either, but they bring em anyway. Rather have the dog than the gun.
Of course ordinary traffic stops involve guns;every police officer I've ever seen making traffic stops has a holstered pistol on his person,but the pistol doesn't sniff your car! The pistol is there if the police officer needs to protect himself form a driver or passengers who are violent, otherwise the pistol is passive.