It's not even about that. You absolutely don't need those tolerances for a cup holder. An assembly line will fuck it up regardless. You use tolerances like that when needed - in jet engines or turbines. Insisting on those numbers on a car is plain stupid - it isn't better (other than the ego boosting "my car has high tolerances where nobody cares") than just doing it like every other manufacturer does it. It's a waste of money plain and simple.