There’s plenty of papers showing exactly this. What do you think has driven productivity? People simply bring smarter?

The fact is capital expenditure from company or investors has bought machinery, compute, pipelines, transport, and massive investment to make those workers more productive for decades. As such, the returns to capital as a share has increased. Those places able to deploy capital to add productivity win over those that don’t.

And real total remuneration across all quintiles has increased significantly. BLS among others has all historical data to check.

If/when there’s a period where there isn’t more gains to be had by more investment per worker, and workers become more productive via their own skill (education, diet, genetic implants,…), then more returns will flow that direction.

This is all well known, and easily checked.