> People within a country can freely move between cities
This is far from universally true, both because of legal direct constraints on internal migration and because of implicit controls which are the result of economic constraints (which are themselves part of the means by which societies are governed, whether or not they are overtly intended products of state policy.)
This is far from universally true, both because of legal direct constraints on internal migration and because of implicit controls which are the result of economic constraints (which are themselves part of the means by which societies are governed, whether or not they are overtly intended products of state policy.)