I’d argue that listing archaic electronic items on a customs form is the correct way. Law and legal documents should assume a catch-all nature by design to address edge cases and until we can absolutely assure that all Walkman, floppies and similar items are out of public circulation for good, it is wise to list them explicitly on a customs form.

The alternative to this is the usage of “including, but not limited to, phones, mp3 players” which leaves you guessing if something needs to be listed or not.