My reasoning is a little different (and a little more charitable I suppose in its generalization about human nature): I don't want to go step in front of the register with no one waiting in it because I don't want to look like a sociopathic jerk. I also assume that is why most people haven't done so.
At the same time, I know as soon as someone does step up and do it, people will grumble but the single ad hoc queue will redistribute itself into 3 more balanced queues. I'm usually waiting for someone else to be that sociopathic jerk.
What I wish is that the manager of the store gave a little more thought to this issue in the first place.