I believe it's quite symbolic. You can't exactly say that it's the joys of life that drives strippers, lap-dancers, whores, prostitutes and so on. The engine may be running, but no one is driving. Too busy performing dispassionate oral to whomever is riding shutgun and only gives a damn on what's on the outside of her, just so she can pay rent and compensate her manager for all the abortions he had to deal with and all the facial lacerations he's had to patch up for her.
