The funniest part is that in that contraction the first apostrophe does denote the elision of a vowel, but the second one doesn’t, the vowel is still there! So you end up with something like [nʔəv], much like as if you had—hold the rotten vegetables, please—“shouldn’t of” followed by a vowel.
Really, it’s funny watching from the outside and waiting for English to finally stop holding it in and get itself some sort of spelling reform to meaningfully move in a phonetic direction. My amateur impression, though, is that mandatory secondary education has made “correct” spelling such a strong social marker that everybody (not just English-speaking countries) is essentially stuck with whatever they have at the moment. In which case, my condolences to English speakers, your history really did work out in an unfortunate way.
Really, it’s funny watching from the outside and waiting for English to finally stop holding it in and get itself some sort of spelling reform to meaningfully move in a phonetic direction. My amateur impression, though, is that mandatory secondary education has made “correct” spelling such a strong social marker that everybody (not just English-speaking countries) is essentially stuck with whatever they have at the moment. In which case, my condolences to English speakers, your history really did work out in an unfortunate way.