From the start and the trailer, I think many will realize this is not a typical film. It means that you cannot watch it as a story narrative but understand it is a representation, a satire. And what is that satire?
The premise of the film is about losing passion and purpose. The chef's suicidal tendency and the plot of the film was about losing his purpose, his joy and desire to fulfill that purpose. This was reflected also in his conversation with Margot, who also felt that way about her work. And once more with the actor, as the chef called him out as an actor who has lost his purpose.
In the ending, Margot called him out. She said, the chef's one purpose, only purpose was to create food which a customer might enjoy. He failed. That was the whole premise and whole point of the film.
Why did the chef fail? Because of the society's tendency to pressure, to please. When you try to please the impossible, you end up losing your purpose, joy, and desire. This is why chef invited these people, of all he blame as "the ruin of his art, his life."
The ending is straight to the point. Margot did something the chef had been waiting for. She told the authentic truth. Everyone is afraid, they're afraid of the chef. Why? Because they're afraid of offending. Margot never liked the food from the start. She wanted to send it back, and was stopped by Tyler. In the end, at the face of death, she stood up and told the chef the truth, she did not like his food and she has the courage to send it back.
When the chef asked her what she wanted to eat, she remembered the photo she saw in his room. The ONE time chef was ever smiling, back when he started it all as a greasy teen, back when he knew the joy of his purpose as a chef, to serve the food to the customers and not about pleasing status quo. She reminded him of that. Remember what he said towards the end? The pain was almost gone, almost. She took away his pain and reminded him the joy of cooking.
To sum up what is the point of the movie. The restaurant is America, what it has become today. It has become a nation bent on pleasing the unpleasable. The people no longer owns the nation, like the chef, but they are owned instead by wealthy "angel investors." And like the chef, including the rest of the staff, the joy and soul, the purpose of this nation has been eroded away.
The cheeseburger. It represents the heart of America, what we use to be. Like chef cooking that cheeseburger, we remember the 1950s/60s... the joy and purpose of being an American. Remember, Margot specifically asked for "American cheese" and chef commented "it is the best cheese because it melts without splitting." The cheese is the constitution, is what binds us together as Americans... so we would not split... It is the cheese that makes a cheeseburger a "cheese"burger.
The people in the restaurants represent various aspects of the nation.
The young men: Young generation of ambitious go-getters, who only focuses on work and money. This is quite clearly expressed in their dialog.
The old couple: They represent the old political generation who had taken everything for granted. This is why the server asked, "how will you handle it, with right or left?" Also noticed the husband is an "old white male," but in this specific case he has a skinny blonde wife with shoulder length hair and dresses very old fashion. The server chose "left" hand and the chef mocked him as a "donkey." The final clue is what Margot revealed about him to the chef that "rattled" her. These are 4 pretty direct clues who they were specifically satiring.
The movie star and assistant: They represent the washed out name dropping Hollywood, who chef said "has lost their purpose."
The critic and her editor: They represent the media, which with their reviews can give rise or downfall to any restaurant, or as chef said, "how many lives have you ruined?"
The coast guard: Our federal agents like the FBI, CIA, etc... yet they are all part of the kitchen.
Tyler: The "know it all" young college generation, who thinks they know how everything works with their head knowledge but has no life experience. In politics, they talk about how they think they can run the country better, but when really put to the test, they fail like Tyler in the kitchen. This is why his dish is called "the BS."
Margot: As the chef said, "the working class, the service providers," the no-nonsense people who just want a cheeseburger. Remember she said, "imagine if a restaurant doing what it is actually designed to do, serve actual food."
The bread scene:
This is their version of the emperor's new clothes, everyone knew there was no bread, but they played along with the groupthink and pretended it was an actual dish. Margot was the only one who didn't buy into this and called it out there was no food. The young men acknowledged the dish, but wanted special treatment. When no one had bread, they used their names and positions trying to get bread.
Margot re-established the server and customer relationship. She realized all along, from the 1st moment chef talked to her, what the chef was looking for. Remember she she wanted to send the food back before and also reminded Tyler that "you're paying him to serve you."
The chef misplaced her as one of them, the servers. In context to the scene, she is not a server, but a "customer." This is why the last scene was pivotal, he outright said it to her, "you are an eater." This is what led to her revelation. Then standing up as a customer, she returned the menu and asked for a cheeseburger. The chef allowed her to leave when she wanted it to go because the customer is always right.
This is a reminder that in this constitutional republic, our politicians work for us, the people. Like Margot, we need to re-establish and fix this relationship in order for the nation to survive. Otherwise, like everyone else in this restaurant who knew they were going to die but did very little to prevent their own demise, we are simply part of the menu. Chef actually brought out this point when the coast guard came.
But even after Margot got out, they could've all did the same thing and asked for a cheeseburger. As the chef pointed out, they didn't try hard enough to fight back. It was as if they all had already accepted the menu. In the final scene, you can see some of them even thanking chef.
Though some of them tried to escape, they didn't fight back. Margot fought back, against the menu, by sending it back and being authentic with herself and then with the chef.