This was the first question that came to my mind as well.
I and my wife both grew up in public schools; 2,000 miles apart. Both of us took our lunches to school in paper bags or lunch boxes. We ate the meal prepared at the cafeteria only occasionally; maybe a half a dozen times a year, that's all.
My lunch was one or two sandwiches (peanut butter w/ honey, or tuna fish, or deviled ham, or liverwurst), some cucumber slices or carrot sticks, some potato chips/shoestring or Cheezits, a piece of fruit, and a thermos bottle of milk or sweetened tea.
I was an urban youth---my wife grew up on a Midwest farm, but her sack or box lunch was very similar to mine. . . . except, she got more BBQ pork sandwiches and venison sandwiches, because her dad raised pork and hunted the deer in the back woods on the farm. I am still jealous!
Neither of our families had, what they call today, "disposable income." My family was definitely lower to middle middle class, and all my wife's folks' money was in the earth and in equipment.
I remember in the 4th grade, the school's "hot" lunch cost 35 cents, and a half pint of milk was another 5 cents. My folks thought 40 cents per day to be too high, and the lunch sent to school with me could be made then for much less than 40 cents. That was, of course, when a Snicker Bar was 7 cents. And sometimes, Mom threw a Snicker Bar in our lunch.
So, the only reason I see for Mrs. Obama's programs is to further entrench government and socialism.