Google is aware of you making purchases
myaccount.google.com
myaccount.google.com
It appears that there is some sort of manual template work being done to pick up details from common order emails. So they've at times added new stores it can parse the emails from, or more versions of their emails.
And there's funny bugs too, like items where you got a pre-order price guarantee from Amazon that resulted in a small refund... will lead to the purchases tab saying the item was returned.
News at 11.
Many may find this shocking or upsetting however I personally find Google Timeline[1] creepier than this set of data.
It's film at 11.