[O] Latex single dollar math delimiter question

[Jarmo Hurri]

Greetings.

Org manual says that

To avoid conflicts with currency specifications, single ‘$’ characters
are only recognized as math delimiters if the enclosed text contains at
most two line breaks, is directly attached to the ‘$’ characters with no
whitespace in between, and if the closing ‘$’ is followed by whitespace,
punctuation or a dash.

Can someone explain why the single '$' characters below are not
recognized as math delimiters?

a /complex number/ $z = a + ib,$ where

Thanks in advance.

Jarmo