The term "double-opt-in" is spammer propaganda. It falsely implies that getting your email added to a spammer's mailing list, regardless of how it happened, is "opting in".
That term is super widely used in spam-prevention, commercial email sending, transactional email sending, and inbox provider industries.
You can disagree with the phrasing if you want, but that doesn't make it propaganda--not any more than the Orwellian naming of the "No Child Left Behind" act makes the law itself propaganda.
It absolutely is propaganda. If a single verification of consent is "double opt in", then zero verification must logically be "single opt in". The evil option is reframed as good, and the neutral option is reframed as extra good. Anybody who uses it is either ignorant or a spam sympathizer.
OK, fine, maybe I shouldn't use the term. Pretend I said, "I run a mailing list where I want to make absolutely sure that nobody is receiving mail without their active and informed consent and that nobody is unsubscribed without their active consent either." I think my question still stands?