Unless the patrolman is side by side with the motorist, or tailgating them, there is no way in the world you can see someone throw a cigarette butt out the window. To me it’s just a convenient excuse to pull someone over, about like seeing them with no seat-belt on and pulling them over, which is just another reason for stopping someone, then acting like they are a mass murderer on the loose.
Sorry, but that's just not true. I see it all the time and I never tailgate. Maybe I just have good eyes (I did have LASIK), but it's perfectly visible to me when it happens.
I will flat state that you are very wrong. I have seen this way too many times and it is much easier to spot at night what with the sparks and all. I try to resort to a small bit of public humiliation of the drivers by calling them out on CB when I see a trucker do this. I have never had one try to defend their self.