Indeed a free market allows for workers to voluntarily unionise but seldom is it the case that members are free to leave at will. Any form of collectivism yield

Indeed a free market allows for workers to voluntarily unionise but seldom is it the case that members are free to leave at will. Any form of collectivism yields the loss of personal liberty and loss of property rights(members cannot opt out of perpetual membership fees). It doesn't help that most union leaders are disingenuous actors who exhibit acidic levels of corruption only comparable to that of majority of government bureaucrats.