I identify my language as "English English" rather than "British English", though that's really neither here nor there to be honest.
It's similar with German though - in the areas of Switzerland where German is spoken it's almost a different language, same I believe with Austria. Especially the Swiss example, where the dialect is known as "Schwiizertüütsch" which isn't even a real word when looked at through the eyes of someone who speaks Hochdeutsch (standard German)
Though, Australia do call their dialect "Australian English" - at least according to Wikipedia - though why it's not more widely known as that in comparison to British English and American English is a mystery.
To go back to your original post for a moment as well - when the Japanese speak Japanese, it's called just "Japanese" because Japan is the only country (I believe, I may be wrong) where that is a major language - hence less room for dialect changing. Whereas English, Spanish, French and such are spoken so widely that there will be many different permutations thereof flying around. It becomes more necessary to be able to discern between them in that case I suppose, and American and British English in this case are the two main ones which people use for typed communication {where most of the differences between the two actually become apparent}
It's similar with German though - in the areas of Switzerland where German is spoken it's almost a different language, same I believe with Austria. Especially the Swiss example, where the dialect is known as "Schwiizertüütsch" which isn't even a real word when looked at through the eyes of someone who speaks Hochdeutsch (standard German)
Though, Australia do call their dialect "Australian English" - at least according to Wikipedia - though why it's not more widely known as that in comparison to British English and American English is a mystery.
To go back to your original post for a moment as well - when the Japanese speak Japanese, it's called just "Japanese" because Japan is the only country (I believe, I may be wrong) where that is a major language - hence less room for dialect changing. Whereas English, Spanish, French and such are spoken so widely that there will be many different permutations thereof flying around. It becomes more necessary to be able to discern between them in that case I suppose, and American and British English in this case are the two main ones which people use for typed communication {where most of the differences between the two actually become apparent}