You obviously know way more about this than me. I just know that today I saw two polls where more than half the respondents were registered v likely, and I’ve read a couple of articles talking about how pollsters are doing an incredibly poor job of screening.
Could be poor screening, and it could be they're now sampling anyone that will finally answer the phone. Muawiyah's earlier point about Caller-ID is valid. If ours indicates "Blocked" or shows "Unknown Caller" from a number we've never called we don't answer.