If you compare the cheapest burger to the most expesnive cut of steak or something they are. Often people do make such comparisons because they that is what they are cooking at home vs what they eat when they go out. You can buy premade frozen burgers you just microwave to cook as well - I've only seen the price in vending machines where they are more than a fast food burger but you can get them at grocery stores too.

But if you are cooking real meals with similar ingredients it is cheaper to cook at home.