I think historically in farming the family chickens tended to be the woman's domain, as was the family vegetable garden. I know my grandfather was out in the fields during the day, and couldn't really tend to the family animals. But, my grandmother was in the home and the chickens were one of the tools she had to keep everyone fed and maybe contribute a bit to the family income. From caring for them to butchering. Milking was hers as well. This was true of my farming great grandparents as well. So, I think maybe for the same reasons (logistics and it being part of nesting) that this hold even now. This is a major generalization, and I'm talking about the small time chicken owners.
Interesting topic!