The bitcoin as a crypto currency is still very young and has not been noticed by all countries so it just need some time until it gets legalized by the country.
Bitcoin is NOT guaranteed to be legalized. I'm pretty sure the government wouldn't want a form of currency that would be difficult for them to tax, especially if a lot of people aren't willing to pay for their taxes.
Government major issue is the tax problem for Bitcoin users and there are many users who use Bitcoin to get rid from government taxes and at the moment this is not a huge trouble for governments in the world because still there are only few amount of people who use Bitcoin but if the number increases in the future that will reduce a huge income for any government which will be a terrible issue to find money to develop countries specially for countries still under development