This is an idiom which I probably picked up during my Navy days in the fifties. Aside from it's male chauvinist interpretation, it has applicability to many things in life. I will give two contemporary examples:
Question #1. Why would residents of FairOaks (Menlo Park) or East Palo Alto, who benefit from the Sequoia Healthcare District without paying for it, voluntarily tax themselves by annexing to the District?
Answer: They won't.
Question #2. Why would parents spend money on the education of their children when the government already offers them "education" for free?
Answer: Some, who consider the "free milk" to be sour, do pay for an alternative. And, it is not just "wealthy" families!
I'd like to hear some other examples.