If this had come off as a genuine complaint and the waiter was covering their ass, there would be a serving of fries on that plate. If someone is unhappy you have to go a little above and beyond, otherwise they’ll just stay unhappy about having had to call it out.

In this case the waiter clearly took it as a joke, and decided to have a little fun themselves. I hope the plate came with a shiny dome on it and the waiter opened it with a grand gesture.