Easy. Intertia and incompetence. Government is full of paper pushers who hav eno higher wish but to live comfortably on tax payers money until they retire. The key to survival is to do what everyone else is doing, and not to be the first to try anything new.
The good thing is, as soon as someone tries anything new, and it looks like it is a success, the paper pushers will join in as soon as they think it is safe, and try to steal the fame and glory.
This is just how the government and the public sector works.