I was wondering if the libraries would keep record of one’s borrowing history. I believe libraries in my area do not.
It would be possible just to keep record of dollar amount and not history. Obviously, that dollar amount still leaks some information about the patron. It depends on the library system whether or not they even want that kind of information.
For the most part, I believe librarians are quite the privacy rights advocates.
https://boingboing.net/2014/09/13/radical-librarianship-how-nin.html
https://boingboing.net/2015/06/11/librarians-hackers-and-privac.html