I think you under-estimate how lazy the average American is. You might be able to make it at home cheaper & faster, but...
- You need to have the ingredients on hand, most of which will go bad in a week or less (beef, buns, lettuce/tomato)
- You need to clean the pan & any other utensils/plates afterwards
I'm all for cooking at home as much as possible, but admit to picking up McD's occasionally when we're out of groceries & short on time. Kids choose it more than the adults, we'd rather go just about anywhere else (& do, typically).