Is it? You can get a double cheeseburger, small fries and a large soda (the worst part arguably of the whole meal health wise) for 4 dollars at McDonalds. You can skip the fries, and get 2 double cheeseburgers for the same price. The McDonalds app will often give you a large fry for free for the 4 dollar purchase.
Whats the comparable food you can be making for 4 dollars at the grocery store?
Cooking only helps when you can get economy of scale going. And only when you can use up all the ingredients you can bought effectively. Also you need the energy to make the food, if you are getting up at 7am to get your kids to school, then pick them up at 6 (when after school ends) and get home at 630, and then need to cook for 30 minutes, then another 15 to get dishes and everything put away. Your looking at not even being "done" with "work" until 715pm when you started the day at 7am. Acting like the time to cook and clean is free is not productive.