Because it is a peer-to-peer exchange, related to the central authorities have no more money or have to track transactions. Instead, "this action is jointly managed by the network. Technology news
declared " Bitcoin value of a trade-only users who wish to come to accept it. This is a "global, personal, and untraceable," says Britain's Guardian, and "Preferred Financial Libertarians, geeks, business, and, possibly, a system for drug kingpins."
Right now, Bitcoin seems to generate excitement and expectation of would-be speculators and miners as in a gold rush. Lots of people upgrading their computers in an effort to spend some electricity to mine the coins (the goldrush) and lots of people actually buying Bitcoin to sit on them in the expectation that their value will go up and the owner gets a bit richer.
There is precious little going on by way of trading with bitcoins, as far as I understand.