iMessage is not a security or privacy-first messaging app. It is a fun and usable messaging app with decent efforts towards privacy and no user tracking. The only messaging app that goes all the way with privacy is Signal, which I use for most of my communication. But Apple is focused on the user experience, and there are some fundamental trade offs with user experience that are not necessary for most users. Most users are never going to be subpoenaed by the police.
Look, iCloud Backup is the weak link here. I don't actually know if your messages will still be in other peoples' backups even if you turn off iCloud Backup, but I also don't know enough about the security model one way or another to be able to say, and I haven't seen evidence provided. I'm willing to believe that they are, just for the sake of argument.
What I was trying to say is that Apple is trying to make it as easy as possible for people to recover their messages, because this covers most peoples' threat models, which do not include protecting data from subpoena. Signal is great technology but the fact is it doesn't sync messages between devices because they haven't figured out how to do that in a way that's fully secure. This is a feature that tons of iPhone users want and are not willing to sacrifice for higher security. What am I missing?
