Translation:Taxi, por favor.
El and la usually take the place of "the", depending on whether the noun is masculine or feminine, and un takes the place of "a". So...Taxi, please. Taxi, por favor. Un taxi, por favor. A taxi, please. Both are good versus...The taxi, please. It doesn't seem to make as much sense.
First, "u" is not a misspelling anymore, it is slang. Just as there is value in learning Spanish slang, there is value in learning English "SMS style" slang. It isn't about "effort". It's a writing style.
Second, I'd be happy to learn Spanish slang because of how applicable it is to where I live and the people I speak to. While it isn't a spoken slang, people -will- encounter "SMS style" slang if they use the internet and encounter English speakers. Not just American, not just the UK, any English speaker can use it, and a lot of people do. You can have a prejudice against it if you want, but that doesn't diminish the value of learning and being exposed to it.
Third, this is a Spanish lesson. If people are coming into a Spanish lesson's comments to learn English, there's an issue broader there than someone spelling "you" as "u". Sure, I wouldn't be very appreciative of someone misspelling Spanish to me while I'm trying to learn it on a lesson, but your anecdote isn't applicable here. Nobody in these comments are trying to learn English from the comments.
You can ask people all you want to "put in effort", I can't stop you, and you have a right to do so, but your reasoning behind it is backwards. There's no value to having someone type "you" instead of "u" here, in this instance.
Spelling "you" as "u" is not taught in English classes. Duo is teaching and using what is taught in English classes.
Duo's job is to teach us to translate Spanish into standard English. Unfortunately, many native English speakers don't know standard English very well -- they failed to learn what they should have learned in their English classes.
Here is a dictionary reference for "u". It doesn't agree with you that it is a standard spelling of "you." https://www.merriam-webster.com/dictionary/u
P.S., this is a standard dictionary used in English classes. You might consider using it before making claims about English.
PPS. Generally, Duo is NOT teaching slang. It's a big enough job simply to teach standard English. Note also that slang is not a standard or big part of the English teaching curriculum in our schools.
there are a number of situations such as talking about transport, dates, the time, or referring to someone’s identity where Spanish articles don’t behave as you would expect.
my problem with this is that i don't know that context just like i don't know the context of the passport question. i'm expected to assume i'm calling for a taxi, and not trying to get to a specific taxi. i'm expected to assume i'm asking for a specific passport, and not any passport. you may think it's a fair assumption but there are no fair assumptions in education.
Right so im confused! I got this wrong first time as i put "el taxi por favor" so i thought ok fair enough. Then i got "passport please" and put "un pasaporte por favor" which was wrong too!! So i don't understand when to use "el" or "un". I got this again and forgot what I'd put the first time so put "el" again and again got it wrong! Can someone explain so i can get it in my head please!?