Until recently, most households around the world supplemented free-range forage with household waste. Productivity expectations where lower for such birds and they were not the inbreed color varieties that dominate backyards in the US.
I sold a hen that was laying 5-6 eggs weekly to an Amish woman who later complained she was laying hardly any eggs. Turns out she is feeding only scraps and corn. Optimum nutrition is needed for optimum egg production as well as for optimum health.
My cousin only feeds table scraps, scratch grains (occasionally) and lets them free range a cow pasture. They lay just fine but he has more than 1 acre per bird with plenty of cow Patties to attract bugs even in winter They also eat all the seeds that fall out of cows hay and access to gardens come fall/Winter. Giant compost piles etc. If you have the perfect conditions you can get away with it. If you have a typical backyard then production will drop drastically. Certain breeds do flourish in those conditions and others will not.