> If you do have to care, then you no longer "know exactly what you get".
You do know you get exactly what you put in, whether that is é (U+00E9) or é (U+0065 U+0301). When you reference files created by yourself, this is not a problem as realistically speaking, your input method will only have a convenient way of forming one of these, and it will consistently generate the same one every time. When you reference files created by someone else, this may be a problem but no more than e.g. the distinction between file.txt (lowercase L) and fiIe.txt (uppercase i): from the user's perspective, the problem is pretty much avoided by selecting the file using tab completion, TUIs, GUIs, whatever you use.
> e.g. the distinction between file.txt (lowercase L) and fiIe.txt (uppercase i)...
Just want to remind a little but extremely important thing: There's absolutely no guarantees that upper("i") is I. There's at least one language breaks that convention, and you won't believe how a big headache is that.
https://prnt.sc/257kxxa lowercase l and uppercase I are quite distinct. If you're going to select all your filenames with autocomplete, then why argue restrict me to case sensitive filenames?
Windows NTFS is sometimes described as case-preserving, case-insensitive; i.e. if you name a file "Test" it will stay in that case, but if you ask for "test" it will find the file "Test". I don't know whether that happens in Win32 or NTFS, but it seems like best of both worlds; I don't want "case insensitive" where it could show me the name in a different case than I entered.
I don't override the font, either HN or FireFox or Windows is picking a serif font. I assume you didn't explicitly choose a font where different things look the same, but if it rendered 'a' and 'Z' the same glyph, you wouldn't say that was a problem with the English alphabet or with case sensitivity, or anything other than bad font design, right?
You showed a screenshot earlier, I know what they look like for you. :) I don't override the font either. HN specifies a CSS font family "Verdana, Geneva, sans-serif", where Verdana is installed by default on Windows but is not a full sans-serif font, so it's a somewhat odd choice by HN. As for the English alphabet, I didn't say there was a problem with it, just that you cannot reliably tell just from looking at letters which letters they are. In practice it is not an issue.
Frankly, the use case where I make a file to send to a customer "Example Ltd DNS details" and want to open it from a command line happens to me infinitely more often than the use case where I have a file called "fiIe.txt" and want to open it from a command line.
You do know you get exactly what you put in, whether that is é (U+00E9) or é (U+0065 U+0301). When you reference files created by yourself, this is not a problem as realistically speaking, your input method will only have a convenient way of forming one of these, and it will consistently generate the same one every time. When you reference files created by someone else, this may be a problem but no more than e.g. the distinction between file.txt (lowercase L) and fiIe.txt (uppercase i): from the user's perspective, the problem is pretty much avoided by selecting the file using tab completion, TUIs, GUIs, whatever you use.