That's not a "short dash", it is a hyphen with spaces around it (more precisely, an ASCII hyphen-minus, but that's really a hyphen that is overloaded in contexts where a proper typographic minus sign isn't available.) There are shorter dashes than the em-dash, one of which (the en-dash) is the normal print alternative for some uses of the em-dash, set open (with spaces) where the em-dash would be set closed (without spaces).

Also, both hyphens and en-dashes are used as word joiners in different contexts; this is not distinct from punctuation but a form of punctuation.

> anyway, you can not expect everyone to use 4 or more different key combinations depending what style they want.

For very informal writing, sure, people are often, according to their own personal comfort, going to be sloppy and approximate punctuation (heck, they are going to do that with spelling quite often.)

> the only solution is to make firefox, word, etc choose the right dash for word-joining, punctuation, minus, number ranges, etc.

Some apps have tools that automatically handle simple cases, but...it's not simple for software to figure out what your intent is and subsitute the correct punctuation mark (the are all punctuation). The actual solution is, as for other less common punctuation marks to accept that there's going to be lots of variation and substitution of easier-to-access characters in informal writing, while recognizing what is correct and maintaining it in formal contexts. But also recognizing that people that know what they are doing and know their tools are going to often use the correct ones in informal contexts, as well.