Labour share have GDP has held roughly constant throughout the ages, even as we saw massive productivity increases since the dawn of the industrial revolution.
You are comparing apples to oranges here. These are two completely different things.
Image the labour share of GDP could be a constant 100%, but perhaps the top 1% of workers (eg CEOs) get all the rewards and the other 99% get nothing.
(That's not meant to be realistic, just to illustrate that you can have a very unequal distribution despite a high or even growing labour share of GDP. No opinion expressed on whether the statistics you cite are any good.)
That means that some (few) workers may be getting the lion's share (but note that "income" isn't limited to workers, so it may also be none), not workers in general. People are interested in the latter, not the former.
