alt Hacker NewsAccording to the wide definition of grammar, everyone uses some grammar, but nevertheless it's not a category error to say "*this sentence got grammar mistake".
When we speak about the grammar for a language/dialect we imply a prescribed "correct" grammar for a particular community of speakers.
> speak about the grammar for a language/dialect we imply a prescribed "correct" grammar
Not prescribed, rather observed. At least in English where there is no language authority and dictionaries present usage.
The situation is even stranger in Norway where there is a prescribed form but where dialects have essentially equal rights so that the prescription really applies only to formal written Norwegian.