There's actually precedence for Extraterritoriality. In our world. McDonald's did it. Don't think they still have it, but when the IMF was running through one country, they did some pretty stupid things. I'm remembering this from a really slow day in class a handful of years back, but it /might/ have been Jamaica.
The tech is here, or will be. RFIDs, check. SINs? Canada has implemented the 'Green Card', which is a Health Card with extra stuff added in, and I'm sure that in another ten or twenty years, we'll be looking at a shift from that to something even more broad spectrum.
Smartlink? Linux-based.
Megacorps? Pepsi is more powerful, financially and otherwise, than most countries - keeping in mind that Russia is as much a country as every bleeding Balkanized scrap still hanging about in Europe. The bigger countries, Japan, the U.S. China, Russia, Germany, Britain...They are on even terms with most of today's 'megacorps', like Wal-Mart. Statistically, Wal-Mart, McDonald's, and even Burger King all hire, globally, country-sized populations. It's not too far-fetched to say that, if they were considered 'corporate citizens', we'd be living in Shadowrun's setting right now, minus the Meta-hate and Magic and Horrors.
I'm just scratching the surface here. Go sign up to organizations like Sum of Us. Yeah, take it with a grain of salt, like any source, but if you read between the lines, Corps are starting to step up.