“Your basic point of view is that if an issue (like the color mismatch) COULD be caused by wrongdoing, the cops should assume it was and conduct the investigative stop.”
There is two sides to that coin.
Would you want a criminal to switch your plate, ( you likely would never know unless you were stopped) and then commit a crime that pointed back at you?
That could cause you far more problems than a traffic stop to check a non matching plate.
Had the guy not been found with drugs in this routine stop, the cop would have told him to notify the DMV about the color change and sent him on his way.
I would much rather have that than someone driving with my plate.
I’m sorry, but I find your justification for disregarding the presumption of innocence rather absurd.
The coin you speak of is the presumption of innocence or guilt.