Where is the Bono for migration?

Given that

the overwhelming explanation for who is rich and who is poor on a global scale isn’t about who you are; it’s about where you are

and

immigration restrictions are probably the greatest preventable cause of global suffering known to man.

Why are there no celebrity advocates for immigration?

The rest of the article, Charles Kenny in Business Week, is excellent, including the research finding that McDonald's staff in the US earn 2.4 Big Macs per hour, compared to just one third of a Big Mac in India (for identical work producing an identical product).