Not really. Here in Australia, our supermarket duopoloy does the same thing, offering discounts per litre. At the time it all started, the supermarket chains started buying into/acquiring petrol stations and rebranding them. This has been going on for over 20 years.

Recently, both supermarkets sold off their petrol station chains, but the sales included long-standing agreements to continue to offer discounts and loyalty program points for those that shop at the associated supermarket brand.