Why does WhatsApp not encrypt Google Drive backups?

'Why does Google not encrypt your Whatsapp messages'?

As mentioned briefly in the comment above, it is something that we will never really know, unless privy to the agreements between FB and Google.

We can speculate though:

Google makes it's money from data and information. The more information it gathers, the more opportunities it has to make money. Very similar business model to FB in that respect.

Google can also comply with court orders to turn over information if asked. If they used zero-knowledge encryption, they would not be able to do that. I imagine that would make LE very unhappy.

An actual answer is impossible, I'm afraid. If you want to be sure your messages are not copied, or used for marketing or whatever, install Signal and encourage all of your friends to do so. Good luck. It's an uphill battle to fight the inertia of WhatsApp!

Do not confuse end-to-end encryption with the generic idea of encryption.

Encryption: you make the contents of a file visible to a restricted audience, probably including yourself

End-to-end encryption: you create a scheme so that other people having conversations will encrypt messages each other but you make yourself, the owner of the schema, unable to decrypt them even under threat or legal warrant.

One peculiarity of the end to end encryption in messaging applications is that if you lose/brick/format/break your device you are unable to decrypt new messages, as you must generate and distribute new keys. This property would make backups useless if retained.

That is why you must give up e2e encryption. I am not saying that you give up encryption. Theoretically, WhatsApp Inc. (Facebook Inc.) can implement an encryption scheme so that backups are encrypted using a key they own, and Google Inc. cannot read data. That would make Facebook Inc. again vulnerable to court orders to surrender the secret keys to read backups.