Does each government agency have to individually enter into a contract with Microsoft et al.? That sounds wildly inefficient and silly. My guess is that this "user" pulled those numbers out of thin air.
The purpose of a contract isn’t to be efficient with paperwork or describe a high-level view of transactions. It’s a document that very granularly describes those transactions.
Any large organization has many people with the authority to spend money, and each one of those transactions will be supported by a contract.
The contracts are generally for specific products or services, for a specific time. High-level agencies have a great deal of autonomy and also get to pull their needs out of their own budgets. Lower-level elements within an agency (a NASA center, for example) can also have more or less autonomy.
Yeah I shouldn't been more clear in my question. I was more referring to high-level services (e.g. Office). For specific use-cases, it makes sense for lower level agencies to have at least a little autonomy.
Any large organization has many people with the authority to spend money, and each one of those transactions will be supported by a contract.