Translation:Two chopsticks, please.
This would specifically be two individual chopsticks. As KeithWong9 above said, ぜん is used for pairs of chopsticks. So, おはし二本 ("two chopsticks") is the same as おはし一膳 ("one pair of chopsticks")
本 as a counter typically refers to long narrow objects, such as a chopstick (the use of 本 for that purpose dates back to when books were typically written in the form of scrolls, which are cylindrical objects)
I agree with you James. It is ridiculous to use 'Can I get X' as the most common default translation for 'Xをください' when there are so many better ways to make a polite request in English, which unfortunately in many cases are not yet on the accepted response list for each question.
It is much more abrupt than the Japanese sentence, and it is very odd to be so dogmatic about insisting on this translation. Quite honestly, if I were just asked to translate this, I would say "Two chopsticks, please," which is perfectly idiomatic English. Indeed, when I was in college on a long plane trip with a lot of friends, we all tried to learn how to say "Two beers, please" in as many languages as we could muster, partially because that format is acceptably polite in most languages.
You'd be best finding an article about it, but they're basically ways of counting different kinds of things. 本 is for long, thin things, so you can see why it's used for chopsticks
It might seem redundant but it's just the convention (and English has enough of that!), but sometimes it provides information. There was an example in an earlier lesson, I forget the Japanese, but it was basically 'two slices of bread' - the translation was 'two counter', and I'm assuming it was a counter for thin, flat items, something along those lines. So 'slices' and not 'full breads' was implied.
I wouldn't be surprised if there's a lot of that, where you use one counter or another with a particular noun to be more specific
I believe it dates back to a time before general counting/abstract numbers. It might seem strange today, but in the ancient world there was no concept of general counting. Five sheep was not the same thing as five bags of rice or five logs. Each individual type of thing had its own numbers to count it. Then an idea of general counting or abstract numbers was developed. A revolutionary concept: that you could see that for a group of one kind of object you could have a corresponding number of another, different type of object. The relationship between the five logs and the five sheep is this property of equivance. And counting as we know it was born ! I heard a very interesting program on the radio about it. I believe the counter words of East Asian languages are a vestige of this older object specific counting as is the dialect sheep counting in English (yan, tan, tethera etc.)
Counters exist in English, too, just used a lot less. You don't count "papers", you count "sheets of paper", it's not "rices", it's "grains of rice", "strands of hair" not "hairs", "blades of grass" not "grasses", etc.
And contrary to your theory, Japanese has increased the number of counters over the centuries. Old Japanese only had a handful of counters, such as -つ for most things, -たり for humans (which is still used in ひとり (originally a contraction of ひとたり) and ふたり) and one or two others that I can't think of at the moment.
Sumerian is the first written language, and it had general numbers, though it also had classifier terms, I think. Akkadian and Old Kingdom Egyptian also had general numbers. What is the language you are talking about that had a different set of numbers for every sort of word? I would think that the English dialect counting system for sheep may be a trade-specific variation, as occurs with a few other trades in a few languages.
"Could" and "can" are similar, but are used in different contexts. See this thread for some explanations of the differences: https://english.stackexchange.com/questions/1/when-do-i-use-can-or-could
No, in many varieties of English, both spoken and written, "can" and "may" are synonymous. This is true of speakers of a variety of ethnicities and ages (some I assume you do not disapprove of). You may want there to be a distinction, just as I would like the infinitive never to be split or the subject case to be the only acceptable form after "than," when the comparison is between subjects. A language, however, is a social construction, and English has no language authority that could even make a case for excluding such changes in the language. Do some more languages on Duolingo and look to the fora (or probably forums most places) and you will see the fecund diversity of the world's Englishes.
Was told the correct answer is "Can i've two chopsticks, please?" You can't contract Can I have into "can I've" in English this way. I got it wrong because my answer was "Two chopsticks, please." Which I think should be fine. When making a request the "Can I have" is often dropped.
I'm not exactly sure what it is you'd like explained? There are many many different counters in Japanese. 本 is simply the counter for long cylindrical objects like chopsticks, pencils, and trees (makes sense given this kanji uses the tree radical). 二 is not part of the counter, it is the kanji for two. So "Two long cylindrical objects"
According to another comment from cvictoria42 in this very thread, this counter’s etymology would be disconnected from trees, but rather linked to scrolls:
“the use of 本 for that purpose dates back to when books were typically written in the form of scrolls, which are cylindrical objects”
Sometimes it's wrong to use "get" sometimes it's wrong to use "have" sometimes it's wrong to use "please". If you're going to have so many questions with kudasai the least you could do is make their answers all consistent.
"Please give me water" is acceptable. "Can I have a bowl is acceptable" "Can I get chopsticks" is acceptable. But none of those phrasings are interchangeable on questions even though it's the exact same request format. /sigh