The mistake also reveals the constrained imagination: Google could only conceive of offering what they had internally to others, struggled, and continues to struggle.
Amazon didn't try - they just knew that they were good at building high scale distributed systems, and thought they could build services for others. That's what S3 and SQS and EC2 were - built from scratch, not trying to figure out how to externalize the internals.
It's more complicated, but I think everything is at least a substantial layer on top of an internal offering. E.g. GCE runs VMs in Borg using the same physical infrastructure used for other services, but GCE has its own API and virtualized networking on top that hides Borg and was not (at the time) used for any internal services.
Amazon didn't try - they just knew that they were good at building high scale distributed systems, and thought they could build services for others. That's what S3 and SQS and EC2 were - built from scratch, not trying to figure out how to externalize the internals.