To be fair, if you're comparing against McD's, you're comparing the cheapest foods available on both sides. You have a point that the costs tend to converge on

To be fair, if you're comparing against McD's, you're comparing the cheapest foods available on both sides. You have a point that the costs tend to converge on the low end, so if your primary metric is cost it doesn't matter so much. However, when you get past fast food to the mid-range, your average dinner entre at a restaurant is going to be at least $10, while the home-cooked meal is going to be like $5. For food of the same quality, cooking at home is cheaper. The absolute minimum cost of either food is comparable (corollary: there is worse fast food available than you could cook yourself).