I have a coworker who comes from a culture where they only have one name. The solution the Fortune 500 company we work for came up with was to put her one name into both the first and last name fields. She seems to be okay with that solution.
For years I was trying to move a company from multiple fields for addresses to just one big text box. We didn't really do anything with the information, so we didn't need to know your postal code as such. We just need to be able to print a customers address on a label. The amount of systems that for some reason wanted to know every separate part of the address was just crazy, and again never really used for anything. One system would map the address fields into another, from there again mapped into a third system and then mapped into the label print system. Why not just have a text box, and parse that through? I never got that implemented.
The separation is odd anyway, what is the reasoning for wanting to sort by last/family name? I guess it makes it easy to identify clusters (e.g. of families) in a list, but nowadays the spouse keeping their last name wouldn't be grouped in the cluster. And to follow the site's example, if there's the 2 sisters Mao Anna and Mao Zsazsa, they won't be near each other in a list sorted by last name if they put in "Mao" as first name.
You will find target person faster if searching manually and they are sorted by the last name.
Cultural assumptions that date from before the world being as small as it is, more than anything else.
HN is in English, and there's a bias towards stories of people from non-English areas integrating into English-speaking locales (which does not have to be "the US", much broader than that) because that's what gets noticed and told around here. But it flows in all directions and all cultures. I've read plenty of tales of woe of non-Japanese trying to live in Japan and integrate with their legal system and having various woes in the process based around their names not fitting into the legal system. And just like the West slowly gets better about accommodating Eastern names, it slowly gets better the other way around too.
It's a generalized culture-mismatch problem. I'll cop to being sort of the opinion that the "Xty-Billion Things Programmers Don't Know About {Names/Time/Addresses}" can end up being overly harsh as they are generally written, but at their core, they do have a point, and while we may read it in English and the examples the articles write about are about our more Western sensibilities impacting a broader world, every culture has that problem and could have their own equivalent documents written in their own language with their own examples (e.g. "not everyone in the world lists their family name first").