Is this really true? I was hyper-sensitive to rent just out of school. Every $100/month difference meant something I would have to write out of my life. Perhaps it's more true that very young people don't mind cramming 6 people in a house or apartment meant for 3.
This doesn't discount the conclusion, though of older people leaving cities like NY, but I think that's more about poor educational options for kids, rather than higher sensitivity to rent.