The market cap of BTC isn't big enough for them to care... yet.
Rest assured that ALL countries want to tax the hell out of you. Not just the US. The US however will flex its muscles to get its way around the world. The US will drone strike your ass if it doesn't collect.
Bitcoin is really a commodity. Not so much a currency. You can't use something this volatile as a 'currency' (or can you in a digital age?). I think Bitcoin is for the tech savvy commodity trader. Lots of people also hord coins, killing the notion of a currency.
As far as modern global banking is concerned, these are a special group of bankers that make the current monetary system work. And they control it. The Germans call them the illuminati.
People have referred to Bitcoin as the gold rush. It's basically the same thing. Digital gold. Cool commodity. The finite number makes it just that.
Google did their whole analysis on BTC. That's why they invested in OpenCoin.