"Costs" versus True Costs

I've found Edspresso's recent series of posts by contributor Michael Strong on "How to Give Your Child An Expensive Private Education--for Less than $3,000 A Year" quite interesting. It's based on some pretty "progressive" ideas about education and wouldn't be my cup of tea, but I can see how a kid who went through the program would probably be both decently educated and a pretty neat kid. But Strong shouldn't claim it only costs $3,000 a year, because that ignores the major cost of the program: The significant opportunity costs for the labor of parents who must opt out of fulltime paid employment to deliver such a program for their child. An adult who has the verbal, literacy, writing, math skills and personal discipline to shepherd their child through such an educational experience would be a valuable employee for a variety of organizations and, barring significant health or emotional problems or living in an extraordinarily deprived area, it seems reasonable to assume such a person could earn, at minimum $25,000 a year in full-time employment. That opportunity cost brings the true cost of such a program to at least $28,000 a year, which is more expensive that many elite private schools. Now, obviously many parents choose to stay at home with their children for a variety of reasons and that's a perfectly valid decision that I in no way mean to imply anything negative towards. But opportunity costs should always be counted as part of the costs of any decision, whether it's about education policy or homeschooling one's child.