But it IS "Double Opt In"

It is if you want to be laughed at! And the point is not to be laughed at. The people you negotiate with in order to get un spam-blocked have a very rigid view of what is correct and what is "not".

When we opt in to one of these allegedly "double opt in" email lists we give our details and opt in. We do this once.

The email server sends a token to us. We confirm the intent to subscribe by using the token and taking action.

We have thus "Confirmed our Opting In".

Did you see any "double" there? No, nor did anyone else.

The term is, always was, and always will be "Confirmed Opt In".