Ancient Greek apostrophe marking elision

[James Kass via Unicode]

Richard Wordingham replied to Asmus Freytag,

 >> To make matters worse, users for languages that "should" use U+02BC
 >> aren't actually consistent; much data uses U+2019 or U+0027. Ordinary
 >> users can't tell the difference (and spell checkers seem not
 >> successful in enforcing the practice).
 >
 > That appears to contradict Michael Everson's remark about a Polynesian
 > need to distinguish the two visually.

Does it?

U+02BC /should/ be used but ordinary users can't tell the difference 
because the glyphs in their displays are identical, resulting in much 
data which uses U+2019 or U+0027.  I don't see any contradiction.