Your question is an understandable question. Understanding the government system, the franchises, and business of Snow Crash makes up a major part of the book. The best place to look is the opening chapters. That's where you learn that Hiro is a pizza delivery guy for the most powerful government/business/franchise in the area. That's right, a private business is equivalent to a governmental power. The United States as you know it now doesn't exist. Most of the ruling and governing power is handled by private corporations. As a business expands, it does so with franchises. That's fairly regular sounding business, but the franchise is also a branch of that "country" (business). That's why "Mr. Lee's Greater Hong Kong" exists in Los Angeles as a separate country with its own laws. Hiro delivers pizzas for the Mafia. His pizza delivery car is actually considered sovereign territory, because it belongs to that business/country/franchise. I know that I keep using a lot of slashes, and that is because a business operates very much like its own country. It expands its ruling power through franchises.
The economic structure of the world is touched upon throughout the book, but the opening few chapters give the most amount of detail in shortest amount of text. For example.
But franchise nations prefer to have their own security force. You can bet that Metazania and New South Africa handle their own security; that's the only reason people become citizens, so they can get drafted. Obviously, Nova Sicilia has its own security, too. Narcolombia doesn't need security because people are scared just to drive past the franchise at less than a hundred miles an hour (Y.T. always snags a nifty power boost in neighborhoods thick with Narcolombia consulates), and Mr. Lee's Greater Hong Kong, the grandaddy of all FOQNEs, handles it in a typically Hong Kong way, with robots.