One of the reason is that blue collar workers ceded their leverage and bargaining power to unions, that not necessarily have their best interest in mind - unions work in their own interest and that depends on how well corporations can tip that interest in their favour using brown envelopes and other ways.

At the same time the power of workers being able to create their own business and sell their services have been eroded over time, to the point that in some countries it is so regulated it is almost impossible for the workers to organise in small businesses providing services.