Us family vacation for Smith distinguishes between productive and unproductive labor. Productive labor adds value to a thing that it works on, while unproductive labor does not. Agricultural and manufacturing workers are productive, while menial servants are not. Wealth used to support servants merely evaporates. People with profligate lifestyles, such as rich, idle landlords, tend to use more of their wealth in the support of unproductive laborers; hence they destroy or at least do not accumulate capital. International trade theory. Smith argues for free international trade on the same basis as he argued for noninterference with domestic exchange. Us family vacation 2016.