Has anyone really looked into why this is? It's easy to say 'lol greed' and be done with it, but it seems silly to presume that people were any less greedy in the 60's and 70's.
'Globalization' might make a little bit of sense as to why individual companies might pay relatively less taxes to the US government, but I'd need more context than that before I'd be willing to accept globalization as the answer to why production gains aren't really being shared with workers anymore.
If the answer is that collective bargaining has been getting less and less effective over time, why is that?