There are good unions and there are bad unions. Good unions look out for all their members and listen to them.
Bad unions look out either just for the leadership or the top few members of the union.
Bad unions include the teamsters, who went on strike in NY to prevent the papers from doing away with the job that was required to care for the teamsters horses while they were at the paper HQ. THis strike was in the 90s, 1990s, not the 1890s. That is a case of protecting the few (union boss sons who had the do nothing jobs) at the expense of every hard working member of the union who needed the money.
Sports unions are usually terrible looking out for the top few paid players at the expense of the vast majority of average players.
I can not think of any union off the top of my head that has intentions other then itself. The worst are the AFL/CIO, Teamsters and the NEA (a terrorist group).
Of course you can't name them. Good unions do their joba and get no headlines. If a union goal is to get in teh news, it is a bad union because that is not what they should be doing.