> Depends on who you ask. What’s the region in question? What counts as a standard? Is Nynorsk codified by ISO? Et cetera.
A government regulating it by teaching it in school and actively using it in public would be a strong criteria. Alternatively, an established body of literature that serves as a model (that's how written Italian evolved).
> It‘s used plenty in public in Cantonese-native areas
Yes, that's also what I said. However, any official announcements or documents are quite unlikely to use it.
Depends on who you ask. What’s the region in question? What counts as a standard? Is Nynorsk codified by ISO? Et cetera.
> People write Cantonese in private of course
It‘s used plenty in public in Cantonese-native areas!
> that usage is not uniform
Yes, there is a disconnect and different ways of writing down a turn of spoken phrase. Sometimes people wouldn’t know offhand how they would even do it about a purely spoken turn of phrase.