Really?I cant say I frequent supermarket petrol stations often but out of interest what do you think she should have done?
If she moved her car to the non petrol parking spot then no one could use the pump until she had paid for her petrol anyway? In fact that would have infuriated someone even more trying to use an inactive pump.
Her only other alternative would be to pay for the petrol, then move the car, then go back in to do her shopping but no one in their right mind would do that.
As you say, those type of filling stations shouldn't exist!