There was an interesting (!) article on the radio recently about the plight of petrol station owners.
They end up tied to a single product, but many make absolutely no money from the petrol. The petrol is sold on at the same price it comes in for, it simply acts as the attraction to go in the shop and buy a twix. It's the profit on the twix that is the sole income of many petrol station owners. To the point where they've been sold £2,000 worth of petrol and that's how much the petrol company get, £2,0000. If he choses to let you off your penny, he pays that penny to the petrol supplier himself. What's more, if he gets a drive off and loses £50 of fuel, that's his business, the petrol company still want their £2,000 for the £2,000 of petrol.
Problem is, may police forces are now reluctant to do anything about thefts of under £50, even if you have video and plates etc..
They interviewed a couple that were in the process of signing away their petrol station as the average of £150 of drive offs a week was wiping out their family income. They estimated that last year they had a joint income, after losses on petrol, of under £10k and it was killing them. 'Better off on benefits' and all that was quoted.