Someone who eats at your local cafe 15 times isn't a "difficult customer." That person is a goddam hero to you. I haven't eaten at any local restaurant 15 times, living in a city that has good local restaurants. What constitutes a difficult and unprofitable customer in this economic context is not the same as in every other context.
You can say it's ironic that he is "applying a different standard" to the two actors in the story, but that's just point scoring, and reality is subtler. Society holds the two parties to this relationship to different standards. By going to a local restaurant 15 times and paying their higher prices, he has more than demonstrated good faith in such a relationship. He has stayed truer to this restaurant than 95% of customers to local restaurants. The owner, on the other hand, has the obligation of providing excellent customer service, which is what society expects of a local restaurant who charges high prices for their food (the breakdown of this expectation is parodied in the Soup Nazi character of Seinfeld). Given how awesome repeat customers are for local restaurant businesses, it should have been intuitively obvious to the owner that they should have let it slide, or at the most said something like, "well technically this one doesn't count towards the promotion but I'll give it to you anyway this time." The fact that this wasn't obvious to the owner when it's SO BLATANT to us indicates that it's this person's entire mode of thinking. This is supported by the bad Yelp reviews for service the author noted in this comment section.
You can say it's ironic that he is "applying a different standard" to the two actors in the story, but that's just point scoring, and reality is subtler. Society holds the two parties to this relationship to different standards. By going to a local restaurant 15 times and paying their higher prices, he has more than demonstrated good faith in such a relationship. He has stayed truer to this restaurant than 95% of customers to local restaurants. The owner, on the other hand, has the obligation of providing excellent customer service, which is what society expects of a local restaurant who charges high prices for their food (the breakdown of this expectation is parodied in the Soup Nazi character of Seinfeld). Given how awesome repeat customers are for local restaurant businesses, it should have been intuitively obvious to the owner that they should have let it slide, or at the most said something like, "well technically this one doesn't count towards the promotion but I'll give it to you anyway this time." The fact that this wasn't obvious to the owner when it's SO BLATANT to us indicates that it's this person's entire mode of thinking. This is supported by the bad Yelp reviews for service the author noted in this comment section.