You've never built a system for the government I take it? You don't build these things in a vacuum, they approve and co-design the system, drive the technology

You've never built a system for the government I take it? You don't build these things in a vacuum, they approve and co-design the system, drive the technology decisions, require you to use "approved" technologies, ban the use of icky technologies because they aren't on the interoperability list (which locks you into a few vendors, the usual suspects, Microsoft, oracle, etc.), slap on all kinds of additional requirements, force you to use hardware from a cut rate vendor so they can make their 8A quota, and so on. It's nothing like a private company building a system. It's more like being a peasant to a lord. Sure you can do what you want, as long it's exactly what they want to you, when, where and how they want you to do it.