Productivity growth at the bottom end is very low, but wages at the bottom end still need to keep up with the cost of living or people who are in minimum wage jobs will no longer earn enough to survive.
That was exactly my thinking. So the argument is that the minimum wage should keep pace with the cost of living. We, as a society, need to help those who were less fortunate than us, and it make sense to make an appeal to compassion.
This article is trying to argue something else entirely. That we as a society are collectively screwing those less fortunate. The productivity has gone up, and the gains from the productivity go to the rich rather than the poor. While this might be true in principle, this article fails to provide the evidence, as the entire premise is flawed.