Measuring the development of patches of Earth seems ridiculous. But that's exactly what we do. How might things differ if we measured income per natural instead of income per resident?
Nearly a century ago, during the Great Migration, less-educated individuals were the ones who left home in search of better lives. The opposite is true today, with the educated more mobile than ever before, leaving some places in a spiral of decline.
Talent retention is not a key driver of economic vitality. If it were, Chicago and New York City would be in a world of trouble. But that doesn't stop many from resorting to the tired brain drain refrain.