Because Public Education

is one of the last public sector areas for the crooks to exploit, destroy, and create profit for themselves.

It's based on the neoliberal philosophy which says public sector work is bad because it is public.  There is no concept of the common good or that public could be better and more efficient in their twisted view of the world.

Of course the privatizers schemes are lousy and have poor results.  There are certain things in society that cannot be successfully done by the private, for profit sector to any degree, and that includes education.