I, too, have never received them unprompted. And, at least in my experience, they don’t eventually send them unprompted, because I never requested them and never received them, as I had another source.

I never wanted this tests and never requested them, in fact I have no idea how to tell USPS to send me those. It is possible that is a simple form ? Good chance that either someone entered my address incrorrectly or local USPS has some target they need to meet.