Why mushrooms? Why fried tomatoes (a preparation I've never quite seen outside the confines of this meal)? Why those canned beans? Why that hockey puck of hash browns? It's a pretty tasty meal but its makeup seems to be, simultaneously, so unwaveringly rigid and so random. I figure there has to be a reason why.
You may have better luck obtaining an answer if you cross-post to r/AskFoodHistorians.