Permission from the government to protect its citizens and some to prevent money laundering. As far as I know, in my country we are only allowed to invest in crypto, not to use crypto as a payment method. In my opinion, permission is required, because after all, every country has its rules
Exactly, each country has its own policy. If your country has a policy that cryptocurrency is only used for investment then that's good enough. Because countries like China and several other large countries have policies strictly prohibiting the use of cryptocurrency for investment and payment methods.
The principle is that the state can protect its citizens as much as possible, so it is not surprising that the policies made will be adjusted to the country's situation. So it seems like there are those who prohibit it from being used as a legal means of payment, but it is still allowed to be traded or invested.
Big countries like China, because the mining carried out by that country is very detrimental to the environment, so there is a ban, as well as perhaps other countries, because there are other problems. It could be to avoid money laundering from cartels and many other things for every country that refuses.
But with advances in technology, it is possible that every citizen whose country prohibits it can still carry out transactions, but this clearly violates the rules.