When a poor person moves from a low-productivity job to a higher-productivity one, we usually celebrate. The worker is clearly better off; the hiring firm is no worse off; and it’s good for the economy as a whole. Indeed, development is often described as the process of structural transformation, where low-productivity workers (typically in agriculture) move to higher-productivity jobs in manufacturing or services.
But when that same worker happens to cross a national border, we call it “migration” and, instead of celebrating, we start investigating the effects on workers, firms and public finances in the new environment; and on those left behind (the so-called “brain drain”). Instead of promoting structural transformation, we look for policies to manage it.