One of the major differences between US unions and the rest of the world is a ~50 year old legal hangover related to racism. US unions used to be allowed to moderate their support for members (as in “Joe Bag-O-Donuts is a detriment to the company and should never have been hired”). Unfortunately, many unions used that discretionary capacity to refuse to support their African-American members. It went all the way to the USSC, but the upshot is that US unions are required to have a more antagonistic relationship with management because they can’t endorse throwing out dues paying members.