Ask HN: Why isn't UPS leveraging Amazon?

I've been wondering why UPS does not charge Amazon for a percentage of their profit. 5% of any package delivered (or $5000 for every employee who wants to quit). I think of them as Amazon's real employees. Amazon can't goto FedEx (more expensive) and USPS (unreliable). So why isn't UPS using its monopoly on the Amazon monopoly right now?