LOL .... you are kidding, right?
There's nothing to "understand" because it's a complete speculation, obfuscation .... this is not about what their costs are, what the true demand and supplies are ... like in normal honest business.
They all simply "agree" on a pump price in a given region and this is what it is. Don't try to find some sort of logical reason for anything regarding oil ... there's nothing logical about it, except for the fact, that one day it will run out ... but you and me will be long time elsewhere on another "planet".
Last time I checked, it was high winds around the refineries in North America .... LOL
Sounds almost like "Insurance Rates" except those will never run out....LOL
It's interesting that when the price of oil went down they complained about how the economy of Alberta will go into a slump yada yada. Truth is the government has a cut in this