Comment by rezonant

As sibling points out and I have argued strongly for in past discussions here, at issue is Apple's control of texting: That is, the ability for a phone to message any other phone with a text message without requiring the other participant to use a custom app. Only iMessage can do this on the iPhone.

In the consumer's eye, all phones can text, so it is a universal way to reach someone who has a phone number. It removes the complexity of having to coordinate ahead of time with a contact about what messaging service they both have. It's why texting is so popular in the US (along with historical actions by US carriers to make texting extremely cheap and ultimately free)

Once they had this control, they then used it to make texting better only when the conversation participants each had iPhones, which produced a network effect where friends would be incentivized to pressure their contacts to also use iPhones. Apple leveraged convenience, features and security to make this happen.

I don't anticipate Apple's upcoming RCS support to materially change this. If we're lucky, we'll get higher quality pictures out of it, but it's possible to support RCS while not supporting a lot of the features that make RCS better than SMS, such as read receipts, replies, typing indicators, and yes, encryption. Encryption is not a standard part of RCS yet, but it could be made so by Apple forcing Google to standardize their encryption and then implementing it. But it's not in Apple's interest given the above to bother. More likely they will do as their initial complaint/announcement about RCS hinted at: Not even engage on encryption because it's "not part of the spec", leaving iPhone/Android messaging unencrypted.

Google is not blameless here, it's insane that they haven't worked themselves to standardize encryption.