I take that back, they announced encrypted messaging, then never released it, then probably fired the engineer who said it’d be a feature in allo (or whatever their last attempt was).
You are confusing security (no exploits) with privacy (encryption). The iMessage system is really private (no third party not even Apple can read your messages) but traditionally full of security holes (messages once decrypted can harm the rest of your device).
I'm not confusing anything. The entire point of the exploits in question are to BREAK the privacy provided by messenger. Google doesn't provide any in the first place, and actively mines your data. Who needs an exploit when it's never encrypted in the first place?
To further this: you realize NSO isn't selling these exploits to Russian kiddies to steal your bank info, right?
These exploits are used by people like the Saudi Government to uncover a Jeff Bezos affair. They're after politicians/power brokers for the purpose of accessing otherwise secure communications for the purpose of stealing state secrets or blackmail.
Someone that can't get a valid subpoena.
Someone that wants to track anything else you do on your phone outside the messaging app.
This is not something that can be stated as fact unless 3rd party clients for a service exist. Apple can, with complete honesty, claim that messages are encrypted at rest/in transit all they want, but since they publish the only implementation of the client, they can modify it at any time to expose the messages to them, in any number of ways.
[0]: https://support.google.com/messages/answer/13508703?sjid=102...
Anyway, the competitor of iMessage and Messages is WhatsApp. Nobody is sending me SMSes except banks so even iPhone users use WhatsApp to send messages to friends and to groups in my country. If somebody would insist using only iMessage they would be out of the loop. And about Messages, well, I don't have that app, I receive no SMSes, I still communicate with everybody so I guess that nobody uses Messages too.
The issue (I think) you are referring to is that if you enable iCloud backup[2] or iCloud for Messages[3] (both of which move effectively move the storage of the messages to the cloud, either as part of the device backup or as the canonical representation that devices sync from respectively) then the messages decoded on device will be stored in blobs that iCloud has the keys to unless you enable Advanced Data Protection.
[1]: https://support.apple.com/guide/security/how-imessage-sends-...
[2]: https://support.apple.com/en-us/HT211228
[3]: https://support.apple.com/guide/icloud/what-you-can-do-with-...
Though it can fall back to SMS in case you don't have data, which isn't E2EE. I'm not sure what the UX flow is like in that case, whether it warns you and asks for permission to send over less secure channel.
I was under the impression that this is a 'proprietary' extension between Google devices, and that there was no RCS-standard-based E2EE:
> The RCS specification defines several types of messages. Our implementation of E2EE uses varying strategies for encrypting each type of message to maximize user privacy while still adhering to the RCS specification.
* https://www.gstatic.com/messages/papers/messages_e2ee.pdf
They use "vnd.google.rcs.encrypted" in the Content-Type header.