I assume the cost of the children's formal education (private school might have discounts for employees, but they still probably have to pay some fees), plus possibly the lower salary of teachers might have been a factor. (also daycare costs for the kids not school going age yet)

If they are saving money by not paying school fees, and having to transport family and wife to the school/daycare everyday, and they are getting a professional qualified teacher at home, with a very favourable teacher : student ratio and unlimited teaching time....

well I can understand why they are willing to take the hit of losing the teacher-spouse's salary.