I think there's something to be said in favor of company-specific unions vs. industry-wide unions. The optimal situation would be one in which Amazon workers form an Amazon-wide union and end up with voting seats on the corporate board, to which they'd elect representatives. As I understand it, this is a bit how VW works in Germany.

The notion that a corporation's employees should have the same 'stakeholder' role as a corporation's shareholders might seem to be a radical notion. It would require re-imagining the corporate board's role: worker value and shareholder value would have to be balanced. This seems like a much fairer system of governance, and also has the benefit of partially democratizing corporations.