What makes unionizing so divisive at Amazon?

I see the strikes going on today and I think it’s so amazing that there are those willing to stand for what they believe. At my location I see the voice board has some mixed feelings. Some people have posted the copy paste union message which I don’t think is very effective, posting the same copypasta five times. Others think Amazon doesn’t need a union here as they mention higher than average pay, college tuition assistance, etc.. I live in Colorado Springs and the cost of living is one of the highest in the country, amazons wages as high as they are still don’t cover the cost of living. Do you guys hear and see things similar at your locations? Why do you think it’s such a hot topic?