All of the people claiming Volcker was responsible for killing unions and decreasing the labor share of income should think about this: the European countries raised interest rates at the exact same time, and their unions and labor shares are doing fine. 
Maybe Volcker was right to raise interest rates and squash inflation at the expense of two recessions. And maybe he wasn't right. But he wasn't responsible for the long-term decline of unions or worker bargaining power in the U.S.
Also ask yourself why all the other rich countries raised interest rates at the same time Volcker did. The answer is either "they were trying to prop up their exchange rates against the dollar", or "inflation was spiraling out of control and everyone wanted to crush it".
