>living standards for the average American have regressed in many ways since the 1970s,

With women's entry into the workforce plus the 1964 Hart-Cellar Act's lifting of immigration quotas the workforce more than doubled in the 70s. At that rate how was work compensation ever supposed to keep up? I'm not saying the trade-off wasn't worth it, but you can't 2-3x the labor pool and then pretend we don't know why wages decreased while competition for scare resources increased.

This is an extremely simplistic reading of a complex real-world issue. There multiple other factors that almost definitely dominated the changes you cite. Including population growth, other massive changes in the regulatory, political, economic, and technical environment... Point being, mentioning one shift in the labor supply is really not a useful frame for "the state of labor in the US."

If we ignore the flaws of capitalism for a second, we could have shortened the work week.

Knowing a reason for wages to drop is not the same as it being acceptable.

lm28469 was responding to the previous poster's specific claim that we now work longer hours "than ever".