okay so here’s the explanation of why this happens
tune is a loanword from french, related to the word “tone”. idk how the o became a u, but that’s not important really. it’s the same deal as tube and tumor, it starts with the sound ty- in british english (and others), and the sound t- in american english. so, in american english, that y-sound was lost after alveolar consonants (t, d, n, l, r, s, z, and also probably th?). that’s why british people pronounce “new” like “nyoo” while americans say “noo”, that’s why british people pronounce “duty” like “dyooti” while americans say “dooti”, etc. so in that sense, “tyoon” is actually the original pronunciation of that word as far as english goes, anyway. pronouncing “u” as “yoo” comes from an approximation of the french “u” sound, which is made by saying the sound “ee” but with your lips rounded. english didnt have that sound, so it unpacked it into having an ee-like semivowel (y) glide into a rounded vowel (oo).
pronouncing words like “tube” as “toob” is closer to their original pronunciation in latin, but that’s not why americans pronounce it that way. we know that this is a case of a y-sound being lost instead of the original latin pronunciation being retained because of words like “cube”, “pure”, “mute”, “unity”, etc. those all still have the y-sound that comes from how they were borrowed into english, instead of the plain u-sound that would come directly from latin.
so, yeah, in a sense, “tune” was originally tyoon (and modern dialects have merged the t and the y into a ch sound since that’s an easier pronunciation and a very natural progression for those sounds that happens in countless, countless languages). but does that make it more correct? no lol, just like how “toon” isnt more correct. they’re both correct for their respective dialects.
correcting one and not the other doesnt make sense, because neither have any more authority than the other. there is no “correct” way to speak. imagine if a french person said “pur”, with that rounded “ee” sound in the vowel, with that odd french r-sound, and a spanish person came and said “um actually it’s pronounced ‘puro’”, with a plain oo-sound and an o at the end. which of them is right? “puro” is certainly not as far from latin “purus” as the french “pur” is, but does that make it more correct? no, lol, they’re two different languages that merely share a common ancestor (latin). likewise, which is correct between “toon” and “tyoon/choon”? neither, they’re two different dialects that merely share a common ancestor (english before general americal split off from it)
and as for people in the notes saying “um america made itunes, they get to name it” lol who cares what apple says