You are right: kids are not that expensive. They eat very little (when they are young) and are perfectly happy with cheap food. They outgrow clothes before they wear them out, as a result there are always people giving away clothes. We have purchased very little clothing for our kids.
The two big ticket items are disposable diapers and college funds, and neither one is strictly a necessity. In addition, once they reach four or five they can start performing simple chores and tasks, and by the time they are teenagers they are capable of doing all but the most complex repairs and are a great help at those.
"Expensive" kids get lessons, sports leagues, TVs, game consoles, cell phones, etc. They never lift a finger to help and grow up with a psychotic sense of entitlement.
I paid my own way through college and never got piano lessons. Do I wish I had those things? Sure, but I hardly wish I hadn't been born for want of them.
Excellent post. Perhaps the start of 'Big Families' Ping List? The practicalities of Family Economics is a great topic.
Particularly for those in our culture who tend to 'invest heavily' in their kids and, so, are too easily scared-away from raising more than 2 kids by the media's semi-constant drumbeat of the 'overwhelming costs' associated. That frightens the 'responsible' sub-culture of our society into 'demographic suicide'.