Yeah, so we could conclude that punctuation is not just a cultural thing, but – to make matters worse – depend on the whims of the font maker as well.

No, both “ and ” characters exist, as well as ".

“Convex” or „concave“ usage varies by language. See https://en.wikipedia.org/wiki/Quotation_mark#Summary_table

To clarify, I was referring to the mere technical fact that only if you type in a character like `“` (U+201C, “Left Double Quotation Mark”) using one font, it isn’t guaranteed to be rendered in the exact same style in a different font.

E.g., when I type a comment on HN and enter said `“` in the input text field, it uses my system’s default monospace font (Courier), which renders the character so that the stroke appears to go from bottom left (thick) to top right (thin). After I submit my comment, HN uses Verdana (the one from my system), which renders the very same character so that the stroke appears to go from the top left (thick) to the bottom right (thin). It’s the same Unicode character, but both fonts happen to render them differently according to how the font maker laid out and mapped the respective characters. (I can observe the same behaviour when I compare both fonts in my word processor, so it’s not HN-specific.)

“” look like 66 99 in conventional serif text fonts, but have wide variation in sans-serif and decorative fonts where they often resemble ‶″ or ″‶ .

„‟ are more consistent in current computer fonts by virtue of their Unicode names strongly suggesting a particular appearance.

    “ U+201C LEFT DOUBLE QUOTATION MARK
    ” U+201D RIGHT DOUBLE QUOTATION MARK
    „ U+201E DOUBLE LOW-9 QUOTATION MARK
    ‟ U+201F DOUBLE HIGH-REVERSED-9 QUOTATION MARK
    〝 U+301D REVERSED DOUBLE PRIME QUOTATION MARK
    〞 U+301E DOUBLE PRIME QUOTATION MARK