no man. They go direct to the source for stock and sell to you with only 1 middle man - themselves.Still more than double price? Supermarkets are middle men themselves so by right they should have some margin already yet they can sell at such low promotion price.
In M'sia we have distributors who sell to dealers who sell to stations, workshops and sometimes they use salesmen to market their products, that's already 3 to 4 middle men.
And whilst we produce the engine oils - the dealers do not have the scale that Tesco global does. Tesco / Giant doesn't just take from the distributor in their respective countries, they take from one source and distribute using their own network. So again yes - economies of scale.
Leinnz brought up a good point too - middle men. Then there's taxes.