Two petrol stations across the road from each other. One has petrol at 119.9c/l the other 144.9c/l.
A) why the huge difference and nothing from ACCC
b) why do people fill up at the one that's 144.9c/l instead?
Because they're going the other way.
And you'll notice the expensive one is always on the side that the most traffic is on, ... into or out of the city.
I've seen them virtually swap pricing, one side to the other, from the morning, to the evening.