Dad didn’t explain in detail but from what I understood, people that kept free range chickens, hens and roosters, often picked up eggs that were not fresh and ended up with chicks in the frying pans.
Farmers like us that had big layer houses for eggs didn’t keep roosters around the laying hens at all. No need for a rooster unless you have setting hens. We did have free range game hens and roosters but not in the laying houses. The game chickens that ran loose were for garden bug control. The layers were mostly the white sex-link hens, I think. We kept about 300 to a house. I was mostly curious at the time why we had to make sure none of the free range roosters got in the laying house. LoL I was a kid.
Yeah, picking up old eggs has its risks.