Well we have gone through times when workers were mistreated; the start of the industrial revolution. It took our grandparents a lot of pain to get the legal protections many workers take for granted. Protections that have been consistently eroded.

Society's creation is a pie, and what % of GDP goes to labor vs capital classes is not fixed. It fluxes and wanes. Over the last 50 years labor's percentage of GDP has fallen consistently.

There are a number of objective measures that support this idea, none of them are perfect, but they tend to show a clear trend: https://en.wikipedia.org/wiki/Wage_share