This is one of the reasons I feel the pendulum has maxed. That said, this takes us straight to the familiar for/against discussion, just with a sharper edge. The union busting debate needs to be had too, but it doesn't tell us much about the type of union they want to build and what that means.
The linked article (thanks) is another case in point, I think. It talks about union busting. Ways in which (like your quote) working conditions aren't good. ... OK.
I don't mean to disparage... IMO, the elephant in the room isn't being addressed. What would a "union win" in amazon (or other young megacorp) mean? More pay, how much more, how would that work?
Let's compare to another field: sports. The UFC is currently experiencing player union agitations. What a "union win" looks like is fairly defined. Other sports leagues are unionized. The realistic range of outcomes is understood.
Forget the conflict side for a moment, what's the goal?