> If the message was actually end-to-end encrypted, Apple wouldn't have the plaintext to give to law enforcement in the first place.
Apple does provide an alternative way to use the iPhone for maximum security with a tradeoff in inconvenience which most would consider unacceptable. Google, Samsung, etc. offers nothing of the sort, and I do wonder whether phone vendors would ever be interested in investing in a feature which essentially destroys the convenience of using your phone.
https://news.ycombinator.com/item?id=32003756
The EFF considers Apple's messaging to be end-to-end encrypted. You could choose to not use iCloud, in which case the only practical way to obtain your messages would be to seize your phone. But since they are end-to-end encrypted, if an Apple employee were able to intercept and decrypt messages, then that would be big security news. If for whatever reason your concept of security is narrowly focused on resisting judicial warrants or state actors, then Android would only be worse here.
> And if iMessages supported RCS, then messages to Android could be encrypted too, but Apple chooses not to support that.
The RCS you mention is essentially Google's own standard, one which US carriers have chosen to reject. If Google could reach consensus with carriers and major phone vendors on a new standard, Apple would likely be forced to accept the new standard. Then RCS would become the true successor to SMS.
There are also other phone apps which use their own custom protocol. In some countries, WhatsApp is the most prominent messaging app.