It does, at least according to the statistics and research we have. Labor share of income has been decreasing during the last few decades. The reason is also simple: without strong interference from governments, markets have a tendency to concentrate and form monopolies. Winners are rewarded with more advantages over their competitors, and over time one or two winners will emerge and get large enough that it's near impossible to compete with them, even if the competitors can resist the urge to get rich quick by selling the business to the dominant players.
Capital also has a much easier time organizing politically than the poor masses, so over time the government will also introduce policies that benefit capital over labor, as we can very clearly see.
