This explicit full definition ensures that your app can
distinguish between and provide the fully nuanced localized
content to all combinations of these country codes.
If a user’s preferred locale is not specified,
then the closest match is used instead,
which likely contains differences to what the user expects.
Flutter only resolves to locales defined in supportedLocales.
Flutter provides scriptCode-differentiated
localized content for commonly used languages.
See Localizations for information on how the supported
locales and the preferred locales are resolved.

Although Chinese is a primary example,
other languages like French (fr_FR, fr_CA)
should also be fully differentiated for more nuanced localization.

Tracking the locale: The Locale class and the Localizations widget