Tor doesn't make your IP address unknowable. There is still a node out there that knows your public IP address and can send packets to you. That's what removes the 4th amendment protection.
Which is plain ridiculous. If I were to move away from everyone and let only one person know my new address so they could forward my mail, I'd have no expectation of privacy because /someone/ knows my real address? If we were to extend it so I changed my name and had a network of people forward my mail to someone else with a different name, then that last person still knows my address and real name. That's exactly what Tor does. It's explicit purpose is for privacy!
It wouldn't count unless maybe that person were your spouse or attorney. Your legal protections sometimes extend to those(though I don't know know this to be true in this example).
At least in Oregon, you're required to have your current address on your state id card or driver's license. You need those to get a bank account or for many other services. You also need it to be updated for voter registration. And if you own a business, often your address will be on the record. So your current address would likely not be protected even if you took all those steps.
I think you misunderstood what I wrote ("making the actual origin of a request unknowable"): of course there is a node that knows your IP address, but no node knows both the actual origin and destination (not even the user who generated the request in the case of hidden services) in any communication inside the network. The objectively reasonable expectation of privacy is in who, from all the IP addresses that are part of the network, is initiating a communication.
Who is entering into a polling place is also "public", yet nobody knows who made certain vote.
Such a node exists, that's true, but this is what the mathematicians would call a non-constructive existence proof: you know it exists but you have no idea how to find it.
