Rubio stages font coup: Times New Roman ousts Calibri

Another issue is due to the font size and font metrics, how much space it will take up on the page, to be small enough to avoid wasting paper and ink but also not too small to read.

So, there are multiple issues in choosing the fonts; however, Times New Roman and Calibri are not the only two possible choices.

Maybe the government should make up their own (hopefully public domain) font, which would be suitable for their purposes (and avoiding needing proprietary fonts), and use that instead.

Only when used in a context where they can be confused. This is a situation where HN is going to give bad advice. Programmers care deeply about that stuff (i.e. "100l" is a long-valued integer literal in C and not the number 1001). Most people tend not to, and there is a long tradition of fonts being a little ambiguous in that space.

But yes, don't use Calibri in your editor.

Yeah because normal people never have to deal with alphanumeric strings...

Natural language tends to have a high degree of disambiguating redundancy and is used to communicate between humans, who are good at making use of that. Programming languages have somewhat less of disambiguating redundancy (or in extreme cases almost none), and, most critically, are used to communicate with compilers and interpreters that have zero capacity to make use of it even when it is present.

This makes "letter looks like a digit that would rarely be used in a place where both make sense" a lot more of a problem for a font used with a programming language than a font used for a natural language.