The United Steelworkers are a perfect example of this. People here on FR often wonder how the union's leadership can support politicians who have helped destroy the steel industry in the U.S. The answer to this is that the union has something like nine retirees for every active worker, and the retirees are all voting members.
What this means is that the union leadership doesn't represent the workers. It represents the retirees. So they will always support politicians who promote issues like Medicare expansion, Social Security spending, pension bailouts, etc. over those who want to keep the U.S. steel industry solvent.
The idea of Unions began, I assume, with good intentions.
But, slowly and deliberately they each...Steel...Auto...Government and finally Teachers have become the worst possible kind of mob rule. A Union takes away any semblance of individualism, which I feel is the best way for one to develop low self-esteem.
There is nothing good that I can think of that a Union does.
Maybe some here have good experiences.