Honestly, I really don't see that there's anything to be gained by telling someone that "a lack of planning on your part . . .". I think it's rude, condescending, and mean. And I think it just makes matters worse when we pat someone on the back for saying it.
I know there are some people who are just unreasonable, of course. But I don't think being a jerk back to them solves anything, and it just means there are two jerks in the interaction instead of one.
I don't think there's anything wrong with making someone think you want to help them, and would if you could, but you just aren't able to. Even if it's not true. The gas station attendant said later in the story something like, "I work closing and not opening, so I don't really know how long it takes to restart the pumps . . ." after she said she told the customer it takes several minutes. Which, ok, whatever. She said that to get out of helping him. But rather than being so smug, would it have killed her to say it with a less abrasive tone? "I'm so sorry, but once the pumps are shut down for the night, we're just not able to restart them until the next day." She would still have accomplished the same thing - not helping the customer. But at least she wouldn't have appeared to get such satisfaction out of it.