The bigger question is why Google is reading and extracting this data from my email id? I don't feel safe and secure. God knows what else they are reading from my mailbox.
If you are a merchant, there are standards for sending package/order information in a machine-readable way in email:
https://developers.google.com/gmail/markup/overview
The purpose is to provide personalized useful features like package tracking. When logged in, you can search for something like "my packages" or "where are my packages". This is a feature that users expect from other assistants (e.g. Amazon Alexa) and email clients (e.g. Outlook).
https://support.google.com/websearch/answer/1710607
The categories that are being extracted for personalized search should be fairly limited (primarily hotels, flights, online purchases).
If you don't feel safe or secure using Google products, you should strongly consider switching away. I personally would suggest Outlook.com, but you could also self-host or use an indie hosting provider like FastMail.
(Most product folks make trade-offs for the average person. There are some great security tech coming out of Google (Security Keys, Chromebooks/Chrome OS) but a lot of the security assumes at least moderate trust in Google.)
Mining your email for keywords and selling you things has been part of their business for a long time. Knowing what you've actually bought is just part of that.
When I book a flight, Google notifies me when the flight is leaving, providing suggestions about when to leave my house in order to make it.
All of these things can be done from reading your email. For someone invested in the Google ecosystem, this is a nice and seamless integration that helps me in my life. That is why they are extracing data from your mail.