You are missing one of the most critical elements in the disruption of unions. That of the substitution of machine for human labour.

Machine labour, ever increasing in its ability to outproduce humans at close to exponential rates completely disrupts the supply/demand curve of human labour as a component of production.

The result is that the more unions try to improve the position of their constituents, the faster companies will replace them with machines, A.I. etc that does not demand higher pay, paid leave, health care and safe working conditions. The result is increasing inequality as income moves from workers to the owners of capital equipment.

A new paradigm is what is needed. One which doesn't assume the value of human endeavor is only measured by the size of a paycheck and compensation package.