Doing work with government, I understand why - ten billion different stakeholders to wrangle, strained budgets (probably not as big of an issue in defense but rampant throughout the rest of gov't), lawmakers changing things mid-project that have a material effect on how the project is carried out, and endless redtape throughout the process. I don't propose FF for gov projects either because inevitably they violate our assumptions by not getting their shit in order which kills the timeline, adds a ton of overhead, and results in a change order anyway which then just starts the whole process of approvals all over again.