Amazon using AWS today is entirely different from the origins of AWS or GCP or Azure being productizations of internal infrastructure.

AWS services have always been their own thing, they happen to be useful so today Amazon utilizes them just like anyone else. That doesn't mean the services started internally.

https://www.networkworld.com/article/2891297/the-myth-about-...

I think you're being a bit too literal here. Did AWS merely fork the infrastructure that Amazon.com runs on and start selling it, no. But are you telling me that it wasn't built on the lessons learned of amazon.com and that it doesn't share some aspects of how amazon.com worked a the time (with improvements to the bad parts)? I don't know the answer and maybe it was a clean-room implementation but that seems unlikely to me.