I cannot believe I'm going to defend...
...some of the stuff I saw when I was is Gov't service but here goes:
For agile to work, one needs and intelligent and engaged customer. A hint of this is found in the question, 'has your customer seen source code?' In a govt to govt context if you show source code, your PM will s#can you immediately. Why? The customer would have absolutely no clue what to do with it. I've seen projects (looking at you DHS) where turnover at the mid-level management to decision maker level was so high that teams could not get on the calendar to brief the wunderkind of the moment before he shoved off for greener pa$ture$. For years straight.
So what do you do when your customer cannot find their own ass with both hands, a flashlight, and a radar set? Make your own best estimate of what they need... somehow get the yes-men, sycophants, and sociopaths above you to agree to a course of action.... maintain laser-like focus on those requirements so you dont piss away resources chasing buzzwords or shiny... and execute. Sounds a lot like the much-maligned waterfall, no?
If you try to go agile you are brought into constant contact with the same yes-men, sycophants, and sociopaths. They've got no insight into whats needed - no technical ability - and are only going to demand more buzzwords and shiby.
The actual users? Nowhere at the table in the bureaucracy. In the "as built" govt waterfall-ish process they get at least some representation because the developers usually hire some to serve as requirements leads early on.
I'm not claiming the as-built process builds products that are optimal, cheap, or necessarily effective. What I'm saying is that its the best you can do in a Byzantine bureaucracy populated by sinecures. Going agile without having a decent customer seems like cruel and unusual punishment, and thats unconstitutional.
That's reality. And that's why I drink and my liver shall be buried with full honors.