Responses

Realistically, it's common bc it's damn hard for people to uproot their lives and move to a new country and start from the ground up. But for rich and powerful people? Easy af. Not to mention in this fictional world, Espers, especially an S-class esper as powerful as the ML, must be sought ofter. Like irl Olympic athletes, countries don't mind issuing citizenships if it means bring in gold medals.
What i don't get about the central agency is if you keep antagonizing your S class esper, you know they can just LEAVE the country and immigrate. I'm sure other countries would welcome an S class esper.