Why are J, U, W considered part of the basic Latin Alphabet?

Question

J, U, W are included in ISO basic Latin alphabet which consists of 26 letters. However,

• The classic Latin has only 23 letters, and J was only used as a variant of I as σ do to ς.
• J, U were not distinguished from I, V in Europe until late Medieval, and were not regard as different letters as late as 18th Century in English.
• Many Europe languages do not have a J or V(sometimes U instead) in their alphabet.
• W, first the digraph UU or VV then ligature as implied in its name, and not included in many European language alphabets, was included in ISO basic Latin alphabet.
• Meanwhile, Æ and Œ which are also common no only even in English but also in Medieval Latin and other Europe languages, however, didn't survive in the ISO basic Latin alphabet.
• Ch, a digraph dated back to 2 Century BC, was included in Gerke's version of Morse code and came to standard by ITU (as do Ä, Ö, Ü), didn't survive, too.

Why were J, U, W included? Is it just a coincidence that English is the only major language that used all these letters and no more in its orthography?

Related: Does any language using the Latin alphabet have a unique name for "w"?

Answer 1

Despite its name, the ISO Basic Latin Alphabet isn't particularly concerned with representing Latin. It was developed in the modern day, so the fact that I~J and U~V weren't consistently distinguished until the 18th century isn't relevant—they're consistently distinguished now.

But the observation that the ISO Basic Latin Alphabet aligns exactly with what's needed for English and not with what's needed for most other European languages is an important one, and gets at the core of the answer.

A lot of early work in electronic transmission of text was done in America, and as such, the early codes used were designed pretty much exclusively for English. It's the same reason why American varieties of Morse code didn't have codes for ß and ø, and why American typewriters didn't have keys for them: they just weren't needed for English, and including them was an additional expense for not much benefit.

In the 60s, American manufacturers standardized "ASCII" (the American Standard Code for Information Interchange) to make it easier for their devices to talk to each other—without any particular consideration given to other languages, for the same reason as with typewriters and telegraphs. And due to the significant influence of American tech manufacturers, the original seven-bit ASCII eventually got enshrined in international standards; variations like eight-bit ASCII and eventually Unicode tended to extend it, not modify the core of it, with non-English letters like ß and ø relegated to higher codepoints separate from the English alphabet.

And thus, the "ISO Basic Latin Alphabet" is just a fancy name for the English alphabet, circa the 1960s and 1970s when these standards were first devised. It's a historical accident, really, nothing more.

Answer 2

Is it just a coincidence that English is the only major language that used all these letters and no more in its orthography?

Is it a coincidence? No.

But that's not the right test, because there are other letters that are not core to the orthographies of all major languages. (k, y, x and q, for example).

A more consistent test then would be if the letter is used in the orthographies of multiple major languages. And on that, j, u and w certainly qualify.

A map of pronunciations of j, and thus implicitly of where j is used. In fact, j does have a pronunciation in Italian, where it is still used in family names and placenames, and pronounced similary to i in the modern orthography.