Google botched up RCS a bit in order to get it momentum, but plenty of carriers do support RCS natively as that's the only way Apple did it with iOS. Google did at least push E2EE options, but those only landed in GSM with RCS Universal Profile 3.0 and I don't think Apple has given a date for when they will support that profile on iOS. That is to say, the problems here are not inherent to RCS itself but the typical adoption and rollout problems of communication protocols.
All that aside, I'd gladly sacrifice the federated service provider flow if there were actually an equally popular federated solution to latch on to with full fallback capability to aid the remaining transition (+ the protocol actually be designed with radio power saving in mind). It's just RCS is by far the closest thing to that full package vs any other generic data messaging service.
This is my guess also. It was published in March[1] this year and I think it was too late to include in this year's iOS 26 release, so possibly iOS 27.
They have promised to implement it:
> "End-to-end encryption is a powerful privacy and security technology that iMessage has supported since the beginning, and now we are pleased to have helped lead a cross industry effort to bring end-to-end encryption to the RCS Universal Profile published by the GSMA," said an Apple spokesperson. "We will add support for end-to-end encrypted RCS messages to iOS, iPadOS, macOS, and watchOS in future software updates." [2]
1 https://www.gsma.com/solutions-and-impact/technologies/netwo...
2 https://www.macrumors.com/2025/03/14/apple-encrypted-rcs-mes...
But since all the networks since 4G, there is no more low-level network support for things like SMS. Everything, including voice and messages, is IP- and packet-based. So the only thing the carrier does anymore is to authenticate that IP connection through your SIM card and bind your identity to the phone number. It actually doesn't really matter if messages are "network native" or through a third-party app, there is no more guaranteed timeslot and reliable delivery that SMS used to have.
And nowadays, RCS is also outsourced to Google by basically every carrier.
So RCS is the same as WhatsApp et al., only that the app you are using doesn't tell you that Google will monitor all your communications in addition to the monitoring your carrier does...