Some things should not be enforced with the death penalty and a library book is one of those things.
This could have been easily handled with a replacement charge for the book and a small fine to pay for the paperwork.
Libraries all have varying policies about fines and returns.
I worked in two university libraries from 1969-2017.
The aging policy that had to have the Board of Regents change it was a small standard replacement fee which did not approach being the modern day cost of the book, plus staff cost for new cataloging record and a maximum fine (not really ongoing day after day added up). Had to be revamped.
One story of the old system. Two Chinese students stole (kept out overdue forever) a number of carefully chosen large format art books worth hundreds of dollars each. They smiling agreed to the pittance of standard fines and paid in cash, walking out giggling. Their plan worked. My old boss was red faced but helpless to do anything.