It's not about Amazon's terrible actions fighting the union. It's about Amazon's exploitative labor practices, the day-to-day oppression that warehouse workers have to deal with.
Also, let's not forget that Amazon has unlimited funds to cover up and distract from their misdoings while the Teamsters do not.
https://www.theguardian.com/technology/2020/feb/05/amazon-wo...
https://www.independent.co.uk/news/world/europe/amazon-used-...