What I am arguing is that the debate is about earnings (i.e. workers making less in relative and inflation adjusted terms) - where the left is in a weak position for the reasons outlined in my missive. However these arguments have some currency with the public, who can easily grasp the concept of being paid more.
A theoretically better argument is one that does not depend on labor-wage exchange, such as one claiming thwarting the development of full human potential, which I like very much. You can do many things with it, including internal critique of capitalism for not living up to its advertised goal of benefit maximizing. The problem, however, is that it is too theoretical and has zero traction with the people to whom the left wants to appeal.
Hence the precariousness of the left position. It can argue for more favorable terms of labor-wage exchange and perhaps gaining some traction with the sellers of labor, but essentially joining ranks with US nationalists and alienating international labor. Otoh, it can argue against consumerism, wasteful consumption and commodification of the daily life, which may fall on the sympathetic ears with many folks overseas, but will be dismissed off hand by the US labor that likes their SUVs, guns and NASCAR races.
Wojtek