Queensland tried regulating petrol prices by having outlets report the sell price 24 hours in advance and then listing that on a website. It didn't work. The small town I lived in had a Roadhouse on the highway and two small vendors (motel & caravan park) within 2 blocks of it. The motel owner would drop his price by 0.1 cents on the Roadhouse advertised price each day to pick up some business, but the system then meant he had to nominate a price without knowing what the Big Boys had nominated. Some days he was dearer.
Using a fuel card generally means getting your fuel at a standard or cheaper price than advertised bowser price. That's why some fuel outlets on major highways appear to be very popular (lots of trucks, cars etc) when the advertised price is higher, but there are other compensations - good food, for example.
Our local TV news shows a graphic, each night, on fuel prices in the region - where the lowest bowser price is in each town / area. We buy our fuel from the Depot, rather than the Servo or Roadhouse, as it is cheaper, but there's no food, toilets etc.