I doubt it mattered much from a financial standpoint whether fans were showing up at Randall's Island, just whether somebody like adidas was willing to subsidize the whole thing for the publicity. High level professional track meets seem to require heavy subsidies from sponsors or governments that are willing to pay to hold meets for the perceived prestige. I doubt the ticket sales in Rabat (Doha, etc.) bring in any more money than in New York - it's just that there must be a sponsor in Morocco with deep pockets willing to pay for the event.