The problem these days is Unicode and “smart” software that changes what is entered.
The former, not so much; the latter, quite possibly.
Is a “-” a hyphen, minus sign, en or em dash? Never an issue in ASCII but they’re all different in Unicode.
ASCII only has a combination “hyphen-minus” character, which makes a poor dash of any length. Most proportional fonts use lines of different widths for hyphen (‐, U+2010), minus sign (−, U+2212), en dash (–, U+2013), and em dash (—, U+2014) [never mind the two-em dash (U+2E3A) and three-em dash (U+2E3B), which are still missing from most fonts], so with proportional fonts the usual challenge is relying on sight alone to distinguish between the ASCII hyphen-minus (-, U+002D) and the Unicode hyphen (‐, U+2010).
If “smart” software is automatically changing e.g. ASCII hyphen-minus characters in scripts or database schemas to Unicode hyphen characters, then perhaps that software isn’t the right choice for working with scripts or database schemas.
Is “A” a capital Latin A or an uppercase Greek alpha? They look identical in any font […]
Dont forget the Cyrillic А (U+0410) and the Cherokee Ꭺ (U+13AA, pronounced “go”). In a font that uses handwritten forms, the Cherokee Ꭺ would look nothing like the other three. I know of one font where none of them look identical — Unicode BMP Fallback SIL — although that feature is by design.