I've seen it happen in passerby and to my father. It is an excuse, yes, but when you are always guilty, officers can pull you over at their discretion whenever they have the slightest whiff of suspicion about you.
The officers argument to my dad was "why would you go so much slower than traffic (this is on i78 in PA, mean traffic is around 75 and he was going the posted 55) if you aren't trying to hide something by going the speed limit" when the back of his covered pickup was full.
Turns out he was just bringing china plates to my grandparents.
He didn't get ticketed for it, but it gave the police a legal reason to pull him over beyond arbitrary suspicions.
With respect, I have a feeling the police officer didn't give your father a ticket because he never intended to give a ticket for that reason; it's probable that it's not actually a real offense and he would have lost that battle in if it was fought. As long as he came up with a halfway decent excuse for pulling your father over, he'd be able to check out the truck without needing to commit to anything. Rational, and effective.
The officers argument to my dad was "why would you go so much slower than traffic (this is on i78 in PA, mean traffic is around 75 and he was going the posted 55) if you aren't trying to hide something by going the speed limit" when the back of his covered pickup was full.
Turns out he was just bringing china plates to my grandparents.
He didn't get ticketed for it, but it gave the police a legal reason to pull him over beyond arbitrary suspicions.