Read receipts for iOS Messages App continue even when turned off in settings

My wife has an SE2 iPhone running iOS 17.1.1.

She has the setting for sending “read receipts” in the Messages app turned off. But her friend on her Android phone demonstrated how she does receive a read receipt upon sending a text to her.

I have read in some postings in various other settings that this problem surfaced in iOS 15.

I take it there was never any resolution? Anybody else able to shed any light?

I am pretty sure that read receipts are only applicable for iMessages (blue bubbles), so would be impossible for a message sent to an Android phone. So perhaps the Android phone is just reporting that the message was sent and not rejected by the carrier?