P PLATES why do we need to display them?

[deankdx]

in QLD when on holidays i tried to buy P plates so my girlfreind could have a drive of the rental car,
no such thing up there, so why do Victoria and other states need them?
yeah L plates are a good idea but how often do you see some clown driving as if they have no experience and dont have P plates.

what is the point of them, a cop attractent or a way of letting us know theres a cute driver possibilty?