That would be because Amazon.com doesn't use AWS.
Other AWS services are also used frequently and heavily. AWS use is strongly encouraged for any new projects.
> "I also wanted to clarify that Route 53 is an Amazon-built and operated service. It is not a re-branding of a third party DNS service. Over time you'll see various parts of Amazon move over to use Route 53."
https://forums.aws.amazon.com/message.jspa?messageID=209251#...