Once upon a time....
I remember doing some Systems Analysis work for an large(ish) education organ. (Yes it was a VERY long time ago)
We talked to all the management to try and figure out what each department did and how it related to the larger organisation. These were the days where most functions were completed via paperwork. When we went to talk to the people at the coal face, we discovered that what the managers thought the department did and what it ACTUALLY did were two different things.
Had a mate who also got roped into some Govt consulting work (Against his will) some 15 years later
He mentioned to me that that although working for a different part of the Govt; The same bullshit was still going on. Additionally, trying to contain the scope creep/churn from the customer was a nightmare! They were constantly changing specs, scope, requirements for parts of the system even completed and signed off ones; every couple of months. When the clients were told by his PHBs that this could be done but it would cost T&M they always said yes, right until the invoices came due; then the client nit-picked every single detail, argued every toss of the coin.
He and his team spent the next ~18 months fighting the customer tooth 'n nail to actually get a system out the door that would actually meet requirements. I believe it was lauded as an shining example of Govt/Private partnership and what could be achieved.
Arguing Waterfall v. Agile in that sort of environment is like arguing the relative merits of paper v plastic bags; While plummeting to the earth from 30,000 feet without a parachute.