Actually, I thought the FMC writeup was fairly believable. Especially considering that they set up shop in the Carib League. Amphibious warfare is what Marines are best at, and any merc company specializing in that kind of tactic fills a niche that most wouldn't focus on, much like the magic and air force merc companies also in the book. Most merc companies range from special forces to standing armies, but they are all primarily ground troops.
As for why you don't see more non-American merc companies, there are two reasons that spring immediately to mind. 1) While North America is not one of the places mercs typically do most of their active work, it is a place with lots of money, and lots of soldiers to recruit from, given that there are how many national militaries dotting the landscape? Combined with the fact that people in North America have the luxury of not living in hellholes like Africa, where tribal influences would undermine any unit cohesion, and any groups already tight enough to be an effective fighting force are already involved in things like piracy other such things... Remember, mercs are people you bring in from SOMEWHERE ELSE because there's too much crazy going on in your neck of the woods, and you can't trust your own people to be skilled (or loyal) enough to do the job. 2) The game itself is Amero-centric. At least, that's how it is in the English version. The German writers focus more on Europe, naturally. The main setting is Seattle, and most of the things the biz goes on revolves around North Am sprawls, with a dose of Japan, Hong Kong, and (only recently) Bogota. Though the Bogota thing is a plot arc that's ending now. So really, other than brief mentions of Lagos (otherwise known as Mos Eisley on a bad day) and occaisional jaunts to Europe, anything you're going to be reading is going to be focused on North Am.
