If you think the API mandate necessitated or created AWS then yes, you misunderstand that memo. The API memo simply mandated a service-oriented architecture. That can run on any compute and indeed predates AWS by several years.

The origins of AWS are entirely unrelated, Amazon simply realized it was good at operating infrastructure. This led to the conception of offering infrastructure as a service. The initial AWS service offerings were built based on Amazon's experience and expertise but were not the literal internal services of Amazon.

See https://www.networkworld.com/article/2891297/the-myth-about-... for more historical details.

Amazon (or Google, or Microsoft) is an anomaly, the things Amazon needs to operate Amazon.com are very very different from what most companies need. The internal services and architecture are purpose built although today they do heavily leverage AWS under the hood. Amazon.com is just a customer of AWS, there's no special installation.

Almost nobody needs Amazon.com's infrastructure (except Amazon) or could even afford to staff it. What people do need are generalized, managed services they can combine for their own use cases.

I'm confused because on the one hand you say that their needs are very different and then on the other hand you say that they are using AWS. Another commenter also pointed out that they are using AWS.

I think the only needs that are likely different are scale, so bigger instances, and the fact that they have a massive legacy infrastructure that can't be easily migrated off of. So that's pretty much what I would expect; Amazon.com does use AWS for new stuff but is still operating a lot of legacy as well.

Amazon uses AWS for some new stuff. New AWS services high up in the stack like AI services run mostly on AWS. Most infra-AWS services run on foundational AWS services like EC2 and S3. Foundational AWS services (EC2, S3, DynamoDB, etc.) don't run on AWS for obvious chicken-and-egg reasons. For all of the things that are done by latecomer AWS services you can count on there being an unrelated internal tool, since clearly Amazon was doing those things before they launched those services.

Amazon builds internal services on top of AWS. The services AWS sells are not Amazon internal services.