Earlier quoted context omitted.
encrypt the data by default and let the third party sellers and customers have exclusive access? Why does Amazon need access to anyone's history?
And what are you going to do when the customer wants to see their purchase history? Tell them "unfortunately, we can't show your purchase history for third party sellers"? What if they want to do a refund? Even if you didn't keep purchase history for customers, Amazon would need to keep purchasing records for accounting purposes. In a multinational corporation you simply can't have money going into a black hole with…
For accounting purposes you can still have line items with less specific category labels.
To be honest you probably don't even need to do much other than gate the data between teams (CSR vs product) and use permissions that prevent bulk aggregation across records for anyone not on a specific non-product team. Lots of businesses have internal policies like this (banks for example).
The reason they don't isn't due to the implementation challenges but because they don't have to (yet).
Should Bezos / Amazon be fined or penalized? Absolutely not. His statements just prove what should already be obvious. Businesses won't police themselves.
This applies to all marketplace platforms where an incentive exists to abuse your access to third party sales data (like app stores).