I think we can correctly guess that this letter writer is a prompt returner of library items.
The Multnomah County Library hasn’t had fines for a few years now. (Given my loose grasp on the passage of time, it could be anywhere from three years to fifteen.)
While I did enjoy the low-key pressure to renew or return my books to avoid fines, I similarly enjoy that I get an email when a book I have checked out has a bunch of people waiting.
I bet you can guess that I would do well in this demerit system.