I don't mean "most efficient" or anything to that end, which is a moral judgement I'm not inclined to consider, but that effectively most practitioners (you know, at home, in small business et al) are women. The phrasing was a bit bad.
Perhaps it's a regional thing, but professional cooks seem to be more often male when I notice them. In particular, I'm thinking of small husband/wife shops where the wife is likely to be the waiter/cashier/etc. (All of those roles rolled into one job.) Perhaps I don't notice the other combination?
I of course agree that traditionally the woman is more likely to cook at home.