Apple's latest system. I turned on the short message reading function in the settings. Why not show that the other party has read it?

That is to say, the other party can see whether you have seen it or not, not what you have seen. After this setting is turned on, if the other party's mobile phone (or software) has this function (showing that the other party has read it), then the other party will know that you have read it after reading the short message; If you turn it off, the other party won't know whether you have read it or not.