There are 2 main reasons why Bitcoin isn’t regulated in any countries yet:

1. The Bitcoin protocol itself cannot be modified by anyone without the cooperation of nearly all its users.
2. The future of Bitcoin market and the possibilities of its community is still unknown.

Some experts also mention that it is impossible to regulate Bitcoin market, but the only way to monitor its activity is when Bitcoins are cashed out.

While Bitcoin transactions do not contain any personal information thus no one really knows who owns how much, it is still possible for authorities to know when the money gets involved in the current financial system where they can monitor. And that is when Bitcoin is converted into another currency.

Everyday, responses from regulatory authorities are changing as some accept it and some ban it.

More details about laws of Cryptocurrency market, you may need to contact the authority of your jurisdiction.