I believe the decline in wages and union membership reflects a shift in how people value themselves as human beings, and their relationship to their fellow man.

I believe the decline in wages and union membership reflects a shift in how people value themselves as human beings, and their relationship to their fellow man. From the data I am looking at, wages started to stagnate (I see no clear decline trend) around the year 1965, which roughly coincides with when women started to enter the workforce in a meaningful way. Could it be simply that the near-doubling of the labour pool pushed the supply beyond the demand, thus depressing prices and forcing people to take what they can get? More recently, we might say robots have helped increase the supply even further. Like you recognized later on in your post, the power of the union comes from artificially restricting the supply of workers to make supply and demand work in their favour, so does it not stand to reason that attitude shift you have observed is a result of the same market economics, not the other way around?