I used for cost comparison a pre-formed hamburger patty from Safeway. If it takes you more than 10 minutes to pull this from fridge, heat a pan and fry, something is wrong. You put it on a bun and put things on it and you eat it. There is no prep area to clean. Wash a pan and your plate. This isn't even a scaling issue, this is negligible time and cleanup for anywhere 1 to 4 people. This is a real side by side comparison as a McD's quarter lb also has nothing on it requiring prep.

I understand what you are trying to say about "fully loaded cost". It's also wrong. The fully loaded cost is still much lower for home vs fast. Unless you insist that you really desire specifically something like deep fried french fries, a specific cooking method that is extremely scalable and well suited to restaurant production and very inconvenient at home. But it is emphatically not true that a meal of similar ingredients/macro nutrition (burger and potato) is in general ever cheaper in fast food form.

If you want to promote the myth that fast food is cheaper, you should cite any other source than that you vaguely remember there being articles 10-15 years ago.