There will be no push back on requirements - nobody is going to say "do you really need that" as they will be reducing the scope of the project and therefore the amount of money made.

Implementations of complex systems in the commercial world (e.g. global ERP systems) often work best when the chance is taken to align the processes of the organization at the same time. I can't see that happening in the context of outsourced government projects - nobody has any incentive to reduce the amount of money spent.