Except that there's no profit to be made in distribution. Even refineries all over the world are struggling to make profits.
Most oil companies derive some 60-70% of their profit from digging the crap out of the ground. Refineries needs to be spectacularly well placed to make a profit refining which is becoming more of a rarity reserved for some of the super-refineries around the world, like the Reliance facility in Indonesia which was the catalyst for closures of some 7 refineries in the Australiasian region over the past 5 years.
The rest of the profit is customer mark-ups at the bowser and selling of ancillary goods and services (BP's biggest profit margin is on coffee not hydrocarbon). The oil companies spend many millions on R&D on the design and layout of stores and co-location with companies like KFC to maximise non-hydrocarbon products that actually make money in the retail sector.
At the bowser, distribution of oil to refineries, and product to the terminal and then to the bowser makes up some 4% of the cost of petrol.