You've created quite a strawman here. None of that is really necessary. Each individual country can legislate how they want Visa to operate within their borders and Visa can take it or leave it. Most major countries or regions have their own payment rails, and if Visa wants to play, they'll have to play by the rules. It's not nearly as hard as you make it out to be. No UN needed.
For each individual country in isolation – relatively easy, yes. What’s hard is universal consensus.
If organization X is considered shady by country A, but totally legit in country B, then Visa operating in both countries A and B cannot allow transfers from B to A. Regardless of what country B and its residents think, Visa would get into trouble with country A. Country B cannot legislate Visa to ignore the laws of A, and there is no recourse for residents of B.
Universal consensus isn't required. It's up to individual countries to decide how they choose to run their payment networks and if that means you cannot transfer between countries, that's a choice they make. They can just achieve this with local or regional subsidiaries, as they already do. Multinationals already handle this exact situation all the time.
Marijuana is a federal crime in the US and basically everywhere else on Earth, but you can buy pot at Canada's government-run pot dispensaries online with your Visa, Mastercard and American Express cards. Like at http://ocs.ca
