I don't know enough about Greek to deeply comment on it. some people do consider using the same code point for apostrophe and citations problematic (it's definitely annoying when doing word segmentation) we also have breaking and non-breaking spaces, as well as tabs. We luckily didn't follow typewriter conventions and collapsed several alphabetic characters!
A semicolon is not considered sentence final, whereas a question mark usually is. This makes it easier for software to auto capitalize. So at least that's possible a use case.
There's also the possibility that Greek requires the top dot to be square or circle, meaning it might in fact have subtle differences in print.
> some people do consider using the same code point for apostrophe and citations problematic (it's definitely annoying when doing word segmentation)
And those people are a menace. "Ball bearings" is a single word with a space in the middle. The only way you're going to get reliable word segmentation is with a natural language parser and a lexicon with an entry for "ball bearing". At that point, you're already recognizing "aren't" as a word; the punctuation isn't really relevant.
On the other hand, if you're not particularly upset about messing up space-including words, there's no real reason to be upset about apostrophe-including ones either.
> A semicolon is not considered sentence final, whereas a question mark usually is. This makes it easier for software to auto capitalize. So at least that's possible a use case.
Such software will need and have a language setting anyway (e.g. for hyphenation). It doesn't have to and cannot rely on code points alone, so the characters (or rather, different uses of the semicolon) needn't have different codepoints.
A semicolon is not considered sentence final, whereas a question mark usually is. This makes it easier for software to auto capitalize. So at least that's possible a use case.
There's also the possibility that Greek requires the top dot to be square or circle, meaning it might in fact have subtle differences in print.