Transport costs drive up the price for non-producing buyers. Also, producer reduce supply when they use their own product, which pushes prices up and reduces t

Transport costs drive up the price for non-producing buyers. Also, producer reduce supply when they use their own product, which pushes prices up and reduces the difference in costs for the fuel (non-producers also drive up the price a when they buy, but that doesn’t help them). I doubt either of those effects is particularly significant, but they aren’t nothing.