Longshoreman unions have an infamous history throughout the world. Even in the USA they have lots of leverage to dictate against things like too much automation.
Perhaps the misunderstanding is because those in the US are so accustomed to the power dynamic between employer and employee being one of controller and controlled, respectively. That's pretty much all employment in the US.
If you can for a moment question that base assumption, and imagine a power dynamic in which both negotiation and normal operations is one of equals, then you may see how that dynamic would lead to different systems.