>Same reason men serving in the military or working abroad or on oil rigs or in long-haul trucking have children?

I don't see how those two situations equate. One is an impossibility, due to circumstance (e.g.: on the battlefield), and other is the willful knowledge that you want nothing to do with their upbringing because, using the OC's words, "I’d rather be earning a large dollar amount (doing something I enjoy) than child-rearing...".

Edit: In other words, there's no direct implication that everyone in the military, working abroad, or long-haul trucking wants nothing to do with child-raising. I'd imagine the situation is actually the inverse but the economic necessity for that work to be done (to provide a living) is what prevents that.