Here is a quote from wikipedia?
The letters I, Q, W, and X of the ISO basic Latin alphabet do not occur in native Turkish words and nativised loanwords and are normally not considered to be letters of the Turkish alphabet (replacements for these letters are İ , K , V and KS ). However, these letters are increasingly used in more recent loanwords and derivations thereof such as tweetlemek and proper names like Washington . I is generally considered a foreign allograph of İ that’s only used in borrowings. Q and X have commonly accepted Turkish names, while W is usually referred to by its English name double u , its French name double vé , or rarely the Turkish calque of the latter, çift ve , which is recommended by Turkish Language Association.
Is this really true since I seems like a common letter in Turkish? Am I missing something?
You quoted something about the “ISO basic Latin alphabet”, so that seems like a question of computer character-set encoding, which is perhaps an interesting subject but has nothing to do with letter frequency in Turkish.
ETA I suppose one could imagine a foreign word that really uses a Latin “i”, “I” in majuscule; in that case you could consider that variant of I as not in the normal Turkish alphabet at all. Also, raw foreign words would not conform to Turkish vowel harmony, and indeed may contain consonants and vowels that do not occur in Turkish at all.
Turkish indeed has the letter I which has a lowercase ı
Turkish indeed has the letter İ which has a lowercase i
Turkish does not commonly have the Latin letter I which has a lowercase as i. If you used the Turkish equivalent, the pronunciation would change depending on where the letter occurs in a word. And that is not the case, Turkish does not change the pronunciation based upon capitalization.
Similarly, Đ and Ð look the same right (maybe depending on font)? In fact, if you copy and paste those, they’re actually different. The former is lowercase đ, the latter lowercase ð. But you might not care unless you’re Croatian or Icelandic.
Yes, what you’re missing is that there are three different letters that look very similar. Two are common in Turkish but do not exist in, say, English. The third is common in English but not in Turkish.