What is the object of allocating fixed overhead costs to products?

Do you know of a better way of doing cost accounting? If you are selling Hamburgers, you are also renting a building, buying electricity, and paying a staff. You logically know that you must recover the cost of the meat, bun, mustard, ketchup, pickle, lettuce, and tomato every time you sell a hamburger. You can not sell a hamburger for less than that amount. You will also waste a little, so you must sell for a little more just to break even. You will have those other expenses. You will have to get the money for them from somewhere. You will need to figure out how many hamburgers you intend to sell in am month and add to each one a few cents for rent, electricity, and staff. Then You calculate your markup. You ask, "Can I afford to rent that place and sell hamburgers?" If you will sell fewer hamburgers, each hamburger will need to carry more cost. If you sell more, each one can carry less overhead. Still, your products have to bring in enough money to pay for the rent, the staff, the utilities, and the depreciation.