I agree that you can get more ingredients, but I can fit a lot of ingredients in a burger that doesn't have to be a mile high. I don't want a quarter inch (6+mm) of red onion on a burger. I don't want a giant piece of lettuce like you mentioned. I don't need thick tomatoes either.

Not that we should eat this, but I can go toasted Brioche bun, light BBQ sauce, 1/5 pound pattie, pulled pork mixed with Mac and Cheese, caramelized onions, light BBQ drizzle, toasted top brioche bun and that's a lot to put on a burger but it can be done easily without your mouth having to be unhinged to bite into it. Someone will probably tell me to throw cheese in there, because we Americans are hurting for a heart attack, but still easily doable.