At lease with Apple stepping into RCS it will get better. Having them contribute research would add more features or at lease actual End to End encryption to the GSM Universal profile. Not just Google and Google Messages.
I think initially RCS features were determined by what Server was hosting it. Google of course wanted everyone to use their profile on their servers... With a great reputation on data retention and privacy Google was of course getting Apples approval.
I thought RCS only works with a server present to act as the host. Having things pass through a Google controlled server was the privacy concern. Since they can easily retain that data in its encrypted form. Which they could likely just as easily unencrypt.
While Apple relies on AWS and Azure for their cloud services. I’m sure they have some sort of agreement or control over the data that limits what Amazon and Microsoft could potentially access.
Apple however can’t guarantee the security or privacy of the Apple user when interacting with an Android phone via RCS. I wonder how they will twist a false sense of privacy