Less children means less (future) income -and other- taxes, so that's probably a reason you won't see that in schoolbooks or in the media. It also goes against the church's doctrine and its' much needed flock. Also, less children means less consumers and that means less profit.
I have no kids, never had a car, have travelled just about six times by airplane, which justifies me being a flexitarian (I eat about three days a week vegetarian meals). Gotta love them lambchops. :-) .
Edit: G.G. Allin knows what's up.