The author there reads the point "Two different data entry operators, given a person’s name, will by necessity enter bitwise equivalent strings on any single system, if the system is well-designed" by thinking in terms of erroneous spelling, but also relevant is encoding issues such as lookalike characters.
Peter Biľak gives a story on bumping into this for the accent in his name. https://www.typotheque.com/articles/lcaron