There are security issues that can require character substitution. And there are different character sets and fonts that can affect how characters are displayed.

The dash substitution seems to have been fixed, or I am doing something differently. There are 4 different symbols:

This is a - hyphen.
This is a − minus.
This is a ' en dash.
This is a ' em dash.

This is how they show up when using pre tags:

  name   symbol  ascii  double  triple  quad
hyphen     -       45     --      ---   ----
 minus     -       63     --      ---   ----
en dash    '      150     ''      '''   ''''
em dash    '      151     ''      '''   ''''

(The pre tag is used for preformatted text that is displayed in a fixed-width font.)

And this is without the pre tags:
is single double triple quad .
is - -- --- ---- .
is − −− −−− −−−− .
is ' '' ''' '''' .
is ' '' ''' '''' .

==== links ====
"An (unspaced) em dash or a spaced en dash can be used to mark a break in a sentence"
"An en dash, but not an em dash, indicates spans or differentiation, where it may replace "and", "to", or "through""
"In informal contexts, a hyphen-minus (-) is often used as a substitute for an en dash, as is a pair of hyphen-minuses (--) for an em dash, because the hyphen-minus symbol is readily available on most keyboards. The autocorrection facility of word-processing software often corrects these to the typographically correct form of dash."
Wikipedia: Dash - Wikipedia

"This essay introduces the basics of hyphens, minus signs, en dashes, and em dashes in one easy lesson."
en.wikipedia.org - Wikipedia:Hyphens and dashes