I assume your comment is that Amazon would lose money if a union happened?
I have had situations where it was not allowed to move a computer monitor from one cube to another - that had to be done by a union employee. Literally taking a unused spare monitor from one desk, and putting it on another employees desk where it was need. ...and there was a formal requisition process to get that done which took two weeks to get through approvals, assignment, and finally have it done.
I have had union workers walk off the job during a major system outage because their facility managers forced them to take their break time. The whole company was down - it was all-hands-on-deck outage due to Hurricane Sandy. The actual union workers wanted to help us get the systems back online for the company, but the union rep wouldn't let them work.
I have had great workers quit or refuse jobs with our company because they knew and loathed the union - not the company, but the UNION.
I don't have any problem with unions at companies that protect the SAFETY of workers, as they are needed in various industrial jobs. ...but at a TECH companies where workers are making six figures, have matched 401k plans, and safe and comfortable desk jobs? ...it just screams "ridiculous" to me.