RCS is not called “end to end” by anyone - even Apple and Google explicitly state it’s not currently E2E encrypted. Apple has pledged to add e2ee to RCS on iPhones but they’re never claimed it’s that way today.
They go out of their way to warn you it’s not the same level of security as iMessage.
Google Messages shows "This chat is now end-to-end encrypted" between compatible devices today.
I agree Apple has been clear on this point. There isn't even a finalized spec for e2e that crosses device manufacturers and cell providers as far as I'm aware.