>There has been wage stagnation and the workers share of the profit has been steadily shrinking ever since the 1970ies. Even the Bosworth piece you link to asserts that much.

The Brookings article asserts that the wage growth stagnation is less severe than what graphs like the EPI's show, and moreover, that the reduction in the workers share of the profit is much less severe than what the EPI graph shows.

The article explains how the primary cause of the slowdown in wage growth is a slowdown in productivity growth:

Still, the data of figure 1 clearly document a major slowdown in real wage growth. It is largely the product of poor productivity performance over the past decade

So I reiterate, that the culprit is slowing productivity growth. The massive rise in social welfare spending, and regulations, since 1950, points to left-wing policies being responsible for the slowdown, and not the free market bogeyman.

And no, the article doesn't say the workers' share has shrunk since the 1970s. It says there has been a slight decrease since 2000:

The basic stability of labor’s share up to 2000 is evident in the minor difference between the growth in labor productivity and real wages (output prices), but the increase in real wages falls short of that of productivity by a substantial ½ percent annual in the 2005-14 period

>I'm not sure I see an argument for that.

The argument is that rent-seeking parties, like those employed in public sector unions, see their incomes increase at the expense of the general population's as social welfare spending, as a percentage of GDP, rises.

This [1] is the situation in California. This [2] is the situation in New York.

>That's fine. We don't have to go back to the rates of the 1950ies. But having a person earning hundreds of thousands of USD per year paying a lower effective rate than a janitor is just cynical exploitation.

The effective tax rate of high income earners is much higher than that of a typical janitor..

>The US industry and manufacturing was doing fine - until the shareholders and the management decided it would be more profitable to offshore production.

Multiple industries went bankrupt. The passenger rail services were crushed under the growing demands of the "brotherhoods". The US Auto industry nearly collapsed. This claim that manufacturing just offshored is unfounded.

>Differences in compensation between management and workers have been continuously expanding ever since the '50ies. So there seems to money around to continue to grow some wages. Just not to grow those of the workers doing the actual work. Strange, right?

Corporate earnings growth has slowed significantly since the 1950s. Productivity growth as a whole has slowed. The US is now inhospitable to large-scale manufacturing, due to laws that put any large operation at the mercy of unions, and regulations that impose enormous compliance costs on them as well.

>Percentage of workers represented in unions has not been as low as today in the last fifty years.[3]

That doesn't matter, because the laws that ensure any large manufacturing operation will inevitably see its workforce unionize, and subsequently be mandated by the government to engage in collective bargaining with the union to the exclusion of all other parties, are still in place. They keep manufacturing from returning.

[1] https://www.hoover.org/research/california-state-government-...

[2] https://www.forbes.com/sites/adamandrzejewski/2020/05/26/why...