The problem is that you don't just want them to SURVIVE, you are expecting them to also be contented and healthy--and hopefully give you eggs. Laying an egg a day is no small feat! You can't get something for nothing. They need adequate protein (with all the essential amino acids), adequate energy, and a diversity of micronutrients of all kinds in order for them to do this.
this doesn't have to mean feeding them "processed pellets" (far from it), but it does mean not ignoring or willing away the hard realities of nutrition.
Cracked corn by itself is a woefully inadequate feed. mainly, it has not enough protein. So if you are wanting to use it, this means you need to supply something else containing enough complete protein along with it. "Kitchen scraps" doesn't shed much light on things, because this could be anything--proteins, carbs, veggies, fiber, fats, or whatever--but if there are meat scraps in it this would contribute to protein in the diet, but there's no way you can provide enough protein to sustain a laying flock with just the scraps you throw away, unless maybe you are running a small abbatoir daily.
I've been trying to figure out for a decade how to use less commercial feed. Fermentation helps. As does systematically including root crops or other energy feeds I grow on farm in the fermented mix.
But I have yet to eliminate it entirely--nor am I convinced I would want to. The farther I get toward growing all of my own feed, the more work it tends to involve--and the more time and thought. There is a continuum of trade-offs between convenience and economy. Sometimes it's worth spending a few dollars to save myself some work.
Where each of us falls on that continuum is ultimately up to them--as is ensuring that their flock is humanely and adequately provided for.
