There are few countries that still maintained the ban on cryptocurrency and just imagine someone that is trading cryptocurrency whether through P2P or other means and got scammed, do you think that he will be ready to report the case to the police? This won't happen because he knows that he might even get arrested for breaking the law of his nation. If you trade Bitcoin or other cryptocurrencies in a country that had out a ban on it, it won't have the gods to report the case because you might even be punished for that. If crypto is legal the a case can be filed.
If a cryptocurrency is prohibited in a country, this does not mean that citizens of this country cannot use cryptocurrencies in other countries. If this citizen is deceived by a fraudster, then it makes no sense for him to seek help from the police of his country. And it also makes no sense to contact the police of a foreign country if he does not comply with all the laws of another country.