There are actually two sets of road rules, it would seem. There are the rules that apply on the actual road, obviously, but then there is this whole other set of much less defined rules that apply when you get off the road, specifically in supermarket carparks.
In fact, within the confines of the supermarket carpark, these rules are so ill-defined they cease to be actual rules and are more like evolutionary guidelines for the survival of the fittest.
Take the simple 'we drive on the left hand side of the road' rule. At my most-frequented supermarket (yes, I'm talking about you, Countdown Richmond Rd) the lack of any road markings dividing left from right has led to the common perception that these boundaries do not apply. It is almost as if people turn off the road and, because everything automobile happens at a lower speed, hey, it's okay if I cut this corner because I just saw a parking space up ahead, right?
Some supermarkets attempt to deal with the left/right issue by attempting a sort of one-way system, defined by large arrows on the ground. For most of us, these arrows are a pretty good clue as to the desired orientation of the traffic flow. But there is always some muppet for whom these arrows do not apply in their need to arrive, park, shop, and then carry on with their oh-so-important day. "Arrows? What arrows? I didn't even see the Indians." Boom, boom.
The mindset that because the supermarket carpark is not an actual road, actual road rules need not actually apply is especially prevalent when it comes to little things like "giving way" and "stopping". The basic human instinct of "see parking space, get parking space" is much more the rule of thumb here. (Or the rule of raised middle finger if there is a dispute over said parking space.) And though we can all sympathise with the fact that at peak shopping times the supermarket carpark is like all of Dante's circles of Hell rolled into one giant circle, this does not give you the license to drive like an idiot when getting the heck out of there.