I retired from education at multiple levels. I would submit that government regulations at both the federal and state level have led to this "growth in administration" due to increased regulations and records maintenance. All of the new social norms have created layers and layers of laws and regulations, both written and understood and there seems to be no end to them. They exist not only in the hiring and maintenance of personnel, in a school they exist in the classroom and all activities.Education and medical industries have increased in price far in excess of inflation primarily because of the growth in administration.
I look at the district I came to in 2005 and see the number of people in admin and support positions (support is much more than admin) and I can't imagine being in the system now. Teachers are crying because they can't get bigger raises even though the state is pumping millions into a system with declining enrollment but increasing social problems. A recipe for disaster.