I disagree. I have seen the exact same thing in a Chinese restaurant near me. “We are just a mom and pop business” is no excuse for screwing customers out of thousands of dollars every week, especially as they know they have been doing so for “quite some time”. I think it’s deliberate, and I’m glad someone is calling them out on it. If anyone is being an arrogant a-hole here it’s the owner. He should have sent him the 12 bucks, fixed the website and offered a free meal.
Notice the game playing the Chinese guy started from the get go?
A normal American restaurant would never have had a problem, the first or second email would have covered it completely.
In the first email the average owner would have understood the problem and the solution, this Chinese guy chose to deliberately blow him off in the very first email, and then started with the games.
My complaint with some restaurants is when they kite up the tip. I had one place put a one in front of the tip increasing it ten-fold and then had the gall to tell me it was the credit card company that did it. I got a copy of the receipt where they put that “1” in front of the tip. I got the full refund of the meal after I had a lawyer friend call them up.