While you are right that regions and other officials can buy lists or labels from national my understanding is that they will not “sell” the information to outsiders. I believe a vendor can buy a mailing but they do not actually get the names, they get the right to mail a piece.
My region has consistently voted not to sell names but that decision would be made on a region by region basis.
I am guessing google too. When you have a name and hometown from the results the rest is pretty easy.