If I understand this correctly the canonical equivalence is more about visual appearance and a user's expectation that two visually identical symbols are treate

If I understand this correctly the canonical equivalence is more about visual appearance and a user's expectation that two visually identical symbols are treated the same. But I find it hard to imagine that a user somehow manages to input equivalent but differently coded symbols on any standard keyboard, especially for a password that a single person will probably always input the same way.