Why do Bentos include Spaghetti?

There is something about bentos that I have always questioned about.

I understand the idea is to get a balanced meal with variety within one container, but I never understood why there is tomato sauce spaghetti, or "Neapolitan", as a tiny side dish.

Not that they taste bad, but they usually come in super tiny portions. It is also another carb to add to a rice-based meal.

I used to think it was because someone made too much spaghetti, but I see it so often nowadays that I feel like people go out of their way to make this just to add a bit into a bento box.

If anyone has an answer, please let me know!