Here is a very interesting piece from 1983 (jstor), Population and Development Review, it is called “Technological Advance, Economic Growth, and the Distribution of Income,” here is one excerpt:
In populous, poor, less developed countries, technological unemployment has existed for a long time under the name of “disguised agricultural unemployment”; in Bangladesh, for instance, there are more people on the land than are needed to cultivate it on the basis of any available technology. Industrialization is counted upon by the governments of most of these countries to relieve the situation by providing — as it did in the past — much additional employment. If I may put this into my own terminology, Leontief is suggesting that at some margins fixed proportions mean many agricultural laborers, or would-be laborers, are ZMP or zero marginal product.
Haven’t you ever wondered how some traditional economies can have unemployment rates which are so high? Those are “structural” problems, yes, but of what kind?
By the way, Brad DeLong cites Larry Summers on ZMP workers:
My friend and coauthor Larry Summers touched on this a year and a bit ago when he was here giving the Wildavski lecture. He was talking about the extraordinary decline in American labor force participation even among prime-aged males–that a surprisingly large chunk of our male population is now in the position where there is nothing that people can think of for them to do that is useful enough to cover the costs of making sure that they actually do it correctly, and don’t break the stuff and subtract value when they are supposed to be adding to it.