Devices support attestation level A display (green or grey check marks in your call logs designate this). If you haven't seen that check mark, then you probably haven't seen many A-level attested calls to your device. As far as device manufacturers go, they only care about A-level attestation, which makes sense as it has full traceback capability.
These days, it's just local shady companies. Think: "Expired Vacation" package timeshare pitches and lately callers asking if I have Medicare A and B.
The Medicare stuff, I assume is some kind of fraud, but the kind where they talk you into being a customer for some service so they can bilk the government for that service (which they may or may not deliver). Fraud, but a more insidious kind - not unlike the auto warranty sales calls (which I seem to no longer get either).
So mostly lead generation for shady domestic companies is what I seem to get. You can always tell, because when you ask the name of the company they hang up on you.
Same, close to zero if not zero (I might have received one late last year or early this year). I do also try to make a bloody nuisance of myself; I'm snoot sure if they have some internal denylist, but I try my hardest to get onto it.
I was led to believe that this is technically allowed so I've been using an app (buzzkill) to junk any text containing the name of a politician.
It's funny though - I live in IL as well, and don't get many political texts.
What I do get matches the ratio of political spam I get across all of my various email accounts: It's 90% one party, and 10% or less the other. A fair amount of it doesn't mention party affiliation, and tries to copy the color scheme and design of the other state party even on their websites (which is pretty brazen). FWIW: I'm not registered with any party at any level and have never signed up for any political newsletter AFAIK.