@skribe Many different written systems as well. For example in Egypt you have at least the following:
Religious/old Arabic as used in both mosque and Church settings (I don't even know whether these are both using the same language, but I doubt it)
Formal Arabic as used in the news, courts, etc.
Informal Arabic as used in every day settings (and which of course has lots of different dialects - Egypt is large country [though maybe not so large when compared to Australia 😆]).
Each of these have their own grammar and vocabulary. And there'll definitely be people in Egypt who’ll only be able to understand 1 or 2 of these (especially because illeteracy is actually still quite common, so lots of Egyptians really only know informal Arabic).