seeallsides.
you made me laugh, I know well what that is.
I have it all the time.
However look at it from the Person 4 perspective, what will 15 seconds do for you. since you did a large shopping, it means that you are in no rush.
sometimes i am that person just buying one small little thing. and there is this person who managed to get in front of me with this overloaded wagon. phew those grueling minutes..