I'm wondering this because is such a real threat to bank system and we all know how banks and governments are tightly linked !
BTC could make people more autonomous, self-resilient, being their own bank. You can use it like cash, making your transaction almost untraceable (or untraceable using e.g. monero or dash or laundry systems) : this is governments worst nightmare, isn't it ?
In worldwide therefore not legal bitcoin it because the governments are not they will not benefit so the system of the bitcoin but other counter is legal because the others make sense and make benefits.
Governments dont make btc illegal worldwide because it is the future of currency. Most of us believe on the potential and power of bitcoin. It will replace our old financial system to a way more advanced and systematic form of financial system.