Sorry to be that person but Mexico is still North America
As far as I understand from what this friend has told me, for Mexico at least, performers say "I'll come for X amount of dollars" and get paid in dollars. It's the promotor's problem how they make up that money. Concert tickets are also equivalently expensive to the US in my experience of when I lived there. Like I paid 150 USD to see Adele and it was like middle of the road.
It'd make sense for her to do a few dates on her own hemisphere to end the year and then leave the transatlantic/transpacific touring for the next. But I'm not her tour manager