> aren't kanji and written Chinese the same language?
No. They're different languages, and the written forms are similar but distinct, akin to e.g. Fraktur - you can read glyphs from the other language, but it's harder and looks odd. (Yes Unicode doesn't have codepoints for Fraktur either, but no real-life world language uses Fraktur, so it's not a significant issue there).
> What's so special about Japanese that it can't be displayed by Unicode? Unicode seems to work fine for Korean and Chinese, and Japanese is basically a hybrid of those two.
Live everyday Korean is written in Hangul, Hanzi are only for historical documents, which limits the impact. Taiwanese glyphs (which you don't mention, but for completeness) get their own codepoints because the Unicode consortium had a certain amount of geopolitical realism. So the only collision in real-life world languages is between Chinese and Japanese, and everything gets set up to use Chinese glyphs by default (or, more often, to exclusively use Chinese glyphs) and Japanese is the only real-life world language whose glyphs don't have proper codepoints in unicode (and are fobbed off with mumble mumble font selection mumble ranges vaporware).
> If the Unicode standard has space for an ever-expanding list of emojis, they can fix their rendering issues with the Japanese language too.
Oh they absolutely could. They don't want to. Also migration would be difficult - you would have to make a hard compatibility break to ensure that people switched to the new standard, otherwise you'd have old documents that look almost but not quite right and now also where e.g. search doesn't work properly (because searching for the new codepoints wouldn't find characters encoded at the old ones, because no-one actually follows the standards for how to do text search, they just search for byte substrings and call it good).
No. They're different languages, and the written forms are similar but distinct, akin to e.g. Fraktur - you can read glyphs from the other language, but it's harder and looks odd. (Yes Unicode doesn't have codepoints for Fraktur either, but no real-life world language uses Fraktur, so it's not a significant issue there).
> What's so special about Japanese that it can't be displayed by Unicode? Unicode seems to work fine for Korean and Chinese, and Japanese is basically a hybrid of those two.
Live everyday Korean is written in Hangul, Hanzi are only for historical documents, which limits the impact. Taiwanese glyphs (which you don't mention, but for completeness) get their own codepoints because the Unicode consortium had a certain amount of geopolitical realism. So the only collision in real-life world languages is between Chinese and Japanese, and everything gets set up to use Chinese glyphs by default (or, more often, to exclusively use Chinese glyphs) and Japanese is the only real-life world language whose glyphs don't have proper codepoints in unicode (and are fobbed off with mumble mumble font selection mumble ranges vaporware).
> If the Unicode standard has space for an ever-expanding list of emojis, they can fix their rendering issues with the Japanese language too.
Oh they absolutely could. They don't want to. Also migration would be difficult - you would have to make a hard compatibility break to ensure that people switched to the new standard, otherwise you'd have old documents that look almost but not quite right and now also where e.g. search doesn't work properly (because searching for the new codepoints wouldn't find characters encoded at the old ones, because no-one actually follows the standards for how to do text search, they just search for byte substrings and call it good).