But why would a teenage writer even think up this lawless society? Perhaps because when trying to make a character seem sympathetic, having them be the victim of abuse at the hands of their parents is pretty much a guarantee to get the reader into their corner. Also, it seems to me that the emo movement is made up of mostly over-privileged white kids who want to be deep and brooding about the indignity they have suffered throughout their lives, but the worst thing that has ever happened to them has been when their parents made them take out the garbage.
Their tortured heroine provides them with an outlet for expressing their agonizing lament while reassuring themselves that their lament is well founded. Finally, it might simply be the product of the writer's own inexperience to create realistic situations and unwillingness to actually do some research.