Petrol is what is known as a "grudge purchase" market - you have to have it, but you hate having to pay for it and there is nothing the service station owner can do to make it a "pleasant buying experience". The high margin overpriced food and drink sales are for time pressured people to buy.
It is a vicious market with lots of lying, cheating, and stealing because Petrol is "negotiable" like cash - and I speak as someone who spent a few years in the industry.
God help Qantas if that is the Alan Joyce business model.