Labor unions have almost always operated in a very high-handed fashion, which is predictable given that they are not organizations based on contract or individual consent. One facet of that high-handedness is their practice of taking lots of worker money in dues, but not disclosing to the members (or anyone else) just what was done with all that money. Supposedly, most of it went into representing workers and getting them better wages and benefits. (Since it is illegal for management to communicate about their contract offers directly to the workers, any increases that eventually are agreed to look like the result of union negotiating, when in fact employers often are quite willing to increase compensation to remain competitive in the market for labor. Thus, unions ironically get credit for the natural operation of the free market.)

Recent changes brought about by Labor Secretary Elaine Chao have compelled unions to disclose financial details they would rather keep secret. The Wall Street Journal was a terrific editorial about it here.