And what makes you think this is the case? Or is it speculation?
> When you delete data in your Google account, we immediately start the process of removing it from the product and our systems. First, we aim to immediately remove it from view and the data may no longer be used to personalize your Google experience. For example, if you delete a video you watched from your My Activity dashboard, YouTube will immediately stop showing your watch progress for that video.
> We then begin a process designed to safely and completely delete the data from our storage systems. Safe deletion is important to protect our users and customers from accidental data loss. Complete deletion of data from our servers is equally important for users’ peace of mind. This process generally takes around 2 months from the time of deletion. This often includes up to a month-long recovery period in case the data was removed unintentionally.
> Each Google storage system from which data gets deleted has its own detailed process for safe and complete deletion. This might involve repeated passes through the system to confirm all data has been deleted, or brief delays to allow for recovery from mistakes. As a result, deletion could sometimes take longer when extra time is needed to safely and completely delete the data.
> Our services also use encrypted backup storage as another layer of protection to help recover from potential disasters. Data can remain on these systems for up to 6 months.
> some data we retain for longer periods of time when necessary.
> We keep some data for the life of your Google Account if it’s useful for helping us understand how users interact with our features and how we can improve our services. For example, after you delete a specific Google search from My Activity, we might keep information about how often you search for things, but not what you searched for. When you delete your Google Account, the information about how often you search for things is also removed.
Incredibly vague, there is no reason email purchases couldn't be included in this category.
> Sometimes business and legal requirements oblige us to retain certain information, for specific purposes, for an extended period of time.
Again, "business requirements" can mean anything at all.