Not to downplay the quality of this work, but being able to extensively plan and specify requirements ahead of time is a luxury that a lot of engineering teams at private companies would love to have.
Also, extensively planning and specifying requirements ahead of time is exactly the opposite of how you pull off delivering well-designed public UX like this.
In the public space you inherently never have a single person who can call all the shots, because organizationally you're accountable to all of the public. Orgs have to be set up to carry on operations resiliently outside having a controlled lineage of management. How you do things is far more directly and heavily influenced by legislation, and that landscape is constantly shifting over the course of your project.
BY FAR the private sector is where engineers can enjoy far more luxury.
In private sector I have met a lot more understanding with regards to managing risk in a smart and scalable way.
They gotta fill a request for proposal in order to outsource a project, then there can be multiple rounds of back and forth to review and revise proposals. That includes quite a few documents, covering requirements among many other things.
It is astounding how high the quality of software can be, if what the software is meant to do is known before it's written.