Despite the massive growth, advancement and advantages of Bitcoin and most crypto currency, why is it hard for most countries to fully accept it is or permit it's exchange?
There's a very simple reason -
Bitcoin is neither created nor controlled by any specific nation!
A lot of countries do not want to legalize something that is not created by them, especially when it is related to money matter directly. Probably that's one of the reasons these countries are still developing.
If I take an example of my country, Bitcoin is neither banned nor legalized. We are allowed to trade or invest in crypto. But we need to pay 30% tax for every profit we make. That's a kind of a daylight robbery.
It all depends on the mindset of the government.