Earlier quoted context omitted.
I very much agree. Every worker should unionize, for the good of us all. Far too much power has been ceded to companies pushing for abusive working practices, that are now largely culturally normalized.
Well, no, I can bargain individually better than a group could try to on my behalf.
1) When workers want systemic reform of an organization.
2) When workers are more-or-less interchangeable.
Software engineers aren't interchangeable at all compared to a factory worker, which is why they have such great individual bargaining power and why (historically) they don't really feel a huge need for a union to represent them. Today, software workers have a bit more interest in unionizing because they want to change their organization's high-level goals (e.g. environmental responsibility, not making tools for warfare, hiring diversity, etc).
But both scenarios apply to Amazon warehouse workers, and union representation would almost certainly be a massive benefit for them.