It’s a totally normal thing for people to make special requests for their restaurant meal when they don’t like a certain type of food or ingredient. A lot of people will ask for no onions on their burger, for example. Sometimes these special requests go a little too far, and servers feel like their customers are cheating themselves.
This person ordered a salad, but asked to hold off on so many things that they basically just ended up with a bowl of plain tomatoes. Tomatoes are delicious and can definitely be eaten on their own, but it probably didn’t make sense to this waiter that they were paying more for less.