Yeah, this is more complex than a double positive isn’t it. Hmm.
“Opt in , by default” would seem to mean you have to opt in, unless some unnamed external condition was met, so normally you would have to choose to participate… which is the opposite of this case , where to NOT participate you must, by default, opt OUT. And if you do not you are automatically committed to participate.
That's correct, but it's a relatively new thing. 150 years ago two or more negatives meant an emphatic no. The switch was caused by Frege and contemporaries.
“Opt in , by default” would seem to mean you have to opt in, unless some unnamed external condition was met, so normally you would have to choose to participate… which is the opposite of this case , where to NOT participate you must, by default, opt OUT. And if you do not you are automatically committed to participate.