"and therefore must have been integrated with his own account, delivered to a completely different account owner?"
There's no mention in the article as to whether the rest of the data was the correct data requested by the applicant. Depending on what else the applicant received other than the voice recordings, it raises the question as to how Amazon store their data and possibly why they are using different keys or identifiers for the different types of data. Was it just a fat finger episode and he got all the data for the wrong account? Or are Amazons systems not capable of automatically linking all data for an account via a single and consistent identifiers?