I don't get why people put tomatoes or lettuce on burgers. They add no real flavor. I do pickles. And even though I hate onions at least I can understand that they do at least provide flavoring so it makes sense to me why someone would use it in their burger. I do use onion powder in my seasoning mix.

But why lettuce and tomatoes? They're even the most common ones. (Obviously cheese too but that adds significant flavor too.)