Re: It was only after the implementation began that they revealed that they couldn't.
Problem is (as others have alreeady stated in other comments) that while Agile might actually work and deliver (or at least do a better job of trying), the public sector is hamstrung by a legally mandated procurement process that all but prohibits it. Procurement process is often so long and complex that central govt. will often have changed colour and changed what local govt. is legally required to deliver before the project can even start.