Asda when owned by Walmart has the policy that they where the cheapest petrol in town which meant that the other supermarkets would also keep their prices down.
Asda was sold to the Issa brothers who also own 1000s of petrol stations under EuroGarages and certainty round here none of the supermarkets are now the cheapest place to get fuel.
and I know they’ve been forced to sell some but with out that completion to keep prices down they’ve run away. And now our local rural garage is cheaper than ASDA, Tesco, Morrisons in the nearest city when it used to alleys be 5-6p a litre more expensive.