America != Norway. American labor unions have (had?) a reputation for corruption, dragging companies down with inefficient and parasitic practices and in some cases being controlled by organized crime (https://en.wikipedia.org/wiki/International_Brotherhood_of_T...).
Isn't the question then about the lesser evil? It's wrong to deny unions on the basis that some people are corrupt. Some people in companies are corrupt too and the US lies squarely in the middle of the corruption index https://en.wikipedia.org/wiki/Corruption_Perceptions_Index?w...
I don't see why America!=Norway is a relevant argument.
Maybe you will be less astounded if you read more about how large countries in terms of areas, population, ethnicities, immigrants have people with different and sometimes conflicting motivations about work conditions.
Conflicting motivations sounds like a very reasonable thing in large populations, in fact. But I have a hard time believing why workers wouldn't unanimously want better pay, better conditions, and more power. I would be curious to see any counter examples!
[1]: https://nordics.info/show/artikel/trade-unions-in-the-nordic...