Take characters like 今 or 骨. Whether the C/J/K variants are the "same characters" or not is semantic, but philosophy aside they are written differently in each language. That is to say, if you are localizing an app into a CJK language, your app would not be working correctly if it displayed Japanese text with a Chinese 今, or vice versa. If you showed it to a user you'd get a bug report.
But such characters have only one codepoint, so unless you have language metadata for your text, you can't render it correctly (which is half of was so bad about the pre-unicode days!).
(Note: Unicode later added "variation selectors", which as far as I know solve the problems mentioned above. I don't know why the aren't in widespread use, or perhaps they are and I'm misunderstanding something.)
Take characters like 今 or 骨. Whether the C/J/K variants are the "same characters" or not is semantic, but philosophy aside they are written differently in each language. That is to say, if you are localizing an app into a CJK language, your app would not be working correctly if it displayed Japanese text with a Chinese 今, or vice versa. If you showed it to a user you'd get a bug report.
But such characters have only one codepoint, so unless you have language metadata for your text, you can't render it correctly (which is half of was so bad about the pre-unicode days!).
(Note: Unicode later added "variation selectors", which as far as I know solve the problems mentioned above. I don't know why the aren't in widespread use, or perhaps they are and I'm misunderstanding something.)