I put "how are you going today?" and was marked wrong. In every day speech I commonly say "How's it going?" to people. So, well... I think I'm right. But I'm unsure enough about it to not want to submit that as a mistake. Is it just NZ/Au that says "how's it going?" or is that common elsewhere?
They want you to translate the sense of the phrase, not it's literal meaning. In English we use to be for this sense, but in French they use aller not etre. Just one of those things. Besides, "how are you going today?" means "In what manner are you leaving today?" - it's grammatically different from "How is it going?".
It won't let me reply to your later comment, so I'll reply to this one.
You said in your comment that you wouldn't say 'How are you going?'. What I'm trying to get across, perhaps poorly, is that that is exactly what I would say. It is extremely common in my part of the world, more so than 'How are you doing?'.
Apologies, it was very late when I was typing that. However, I would still use 'going' instead of 'doing', and stand by my point that it is a valid translation. The French sentence uses 'aller'/'to go' but not in the sense of literally 'going', so why would the English sentence using 'going' but not in the sense of literally 'going', be wrong?
I didn't say it was necessarily. I'm saying it depends on the pronoun. If the pronoun is «ça» and not «vous», then that's exact how it's translated: «Comment ça va ?» = "How's it going?" However, we're not dealing with "it" but with "you," and in English, you wouldn't say "How are you going?" when inquiring after someone's well-being. In intent, those phrases are interchangeable, but I think we have to stick to more than just preserving intent when translating here. Substituting "it" for "vous" implies to the checker that you don't know the difference in pronouns, and that, ultimately, constrains the translation.
I really thought the question was about transportation, so literally the means of going somewhere (although now that I think about it there wasn't anything like that before. Not that Duo never shows me unseen expressions in reviews.) Don't the French ask this kind of question using 'aller'? I'm curious.
I was told by my French teacher that french people would get confused with the pronounciation of this word, and to clarify that the word was in fact "hui", and not "oui" or something else, they would say "Today, on the day of today, that comes to be in French "Hui, Au Jour D'Hui" .