[A_C_Slater]

One could write a whole book on the psychological dynamics of this one phenomenon. But it basically boils down to assumption that if you manange to pass them then that means you are better than them, because it might mean you have somewhere you have to go that is more important then where they are going, or that your time is more valuable than theirs, hence the inferiority complex.

My suggestion is to pass these people and pump your fist at them in celebratory exultation as if your favourite sports team just won The Big One . This will enrage them much more than "the finger" if you do it once you manage to get in front of them.