JT, we've been over this before. You accepted the union propaganda, without questioning. The 40 hour work week was the result of work/motion studies and Henry Ford. After 40 hours, human attention span and energy begins to drop. At 50 hours, there is significant loss to the company. Ford desired the 40 hour work week because he could keep up to 3 shifts working and allow time for his employees to enjoy the product. He encouraged other industries to do the same.
The middle class grew in the US well before the advent of unions.
The middle class came from unions and FDR's programs. Before FDR, the "robber barons" gave us the depression.