This sort of thing works well for individuals. Eg.

https://www.fuelcheck.nsw.gov.au/app/FuelPrice/ByLocation?la...

Then you need the integration into home assistant for your local options.

https://www.home-assistant.io/integrations/nsw_fuel_station/

And an app for ease of use when you're out of your local area.

https://play.google.com/store/apps/details?id=au.gov.nsw.one...

https://apps.apple.com/au/app/nsw-fuelcheck/id1266569551

How does it affect things across the economy for fuel purchase? Haven't seen a study. It would incentive-ise price cutting to increase sales, especially by the independent operators, by essentially advertising the lower pricing for free, is my guess.