Just because it came out of someone’s back yard, doesn’t mean it’s high quality. So many chickens get table scraps and little else. Not everyone is suited to keeping pets, let alone livestock.
– But it generally does in developed countries as the majority of people going through the effort of keeping chickens in that environment are into keeping chickens. You might get some shitty setups, but the norm is decent quality feed and far less stress than large scale commercial setups.
It’s more of a hobby than a “get rich” scheme.
That’s cool, but neither of us have any data, and I’m telling you my experience has witnessed the norm is shitty setups feeding table scraps to half starved hens.