This frustrates me too, if something is "opt-in", that means by default you're not included and can choose to be included. If something is "opt-out", that means you're included and can choose not to be.

But then it gets used to describe the reverse, and we have to add words to clarify.

I once saw a post here with a correctly described opt-in telemetry before, and the top comment here was attacking them for the reverse, thinking it was including them by default, so there's little winning, it's one of those words that has just come to mean it's opposite.