The government is not in a hurry to take bitcoin, because it has an unstable price and everyone is afraid that at any moment the bubble may burst. It is more effectively considered as an additional opportunity for earning.
It is not just about the unstable price or the volatility of bitcoin but rather it is about the control. Bitcoin is decentralized and is also something new and using it possibly has some huge consequences. The governments would rather conduct some study first before they would accept such kind of currency. If the government find some merits on it they will make some move to place it on their system and so a good example is Japan.
Price is not stable and fluctuation is not the reason. The government can easily overcome that easily. At first, bitcoin appeared secret, it was a really free currency, we could call it "outlaws." However, due to its long-term and stable operation, it has gained more attention, but it is still a hard-to-manage currency, and governments are not really ready to do so. Moreover, the forces that oppose the government are the real ones behind and promote the development of bitcoin. That is the difficulty with them.
The government wants to control everything, even drugs and bitcoin is no exception. It's just time that they mastered the principle of electronic currencies and improve the system for more transactions.