Some people have surnames that are difficult to pronounce and get irritated when people get it wrong. And in fact, such phonological differences not only within different regions but also over time too. They are just phonological differences, but the words still make total sense. And they don't do that because they know how language works.
But both sides know exactly what they mean, and to the best of my knowledge they don't slug it out on social media groups arguing which is right. English speakers pronounce the name of the capital of France as 'Pah-Riss' whereas the French (and they should know) pronounce it 'Pah-Ree'. Neither side is 'wrong' - they are just pronouncing words in the way that is most common in where they live. It's the same reason some people in the US pronounce words like Oregano, Aluminium, Duke, Zebra, Yoghurt, Semi, Vase, Buoy, Futile, Anti, Schedule, Herb and Garage differently to the way people in the UK pronounce them. Put simply, a particular region of population will pronounce a word in the way that is most common for the area they are in. It's essentially vernacular - and it relates to the common parlance of the district, region or country that changes the way words are pronounced. In the UK words like 'bath' and 'castle' will differ in pronunciation depending on which County you are in. In fact it can change within regions of the same country. You see, language is a quite wonderful living thing and it changes as you move around the globe. I am from the rainy North West of the UK.
If you are Hawaiian that is exactly how you will pronounce it because you are, errr. Well, I cannot argue with the Hawaiian tongue as being correct, but only IF YOU ARE HAWAIIAN. That's called an 'Okina' and denotes that the pronunciaton should be a soft U, giving you the 'Ook' sound. In fact, in Hawiian the instrument is spelled with an apostrophe type symbol before the U, so it reads 'Ukulele. The Ook brigade are, in the main, traditionalists who choose to pronounce the name of the instrument in the native Hawaiian style. And that is what makes the argument quite so ridiculous. And it's not the first time - many people witnessing the debate were shaking their heads thinking ' please.not this again.' Both sides fight their corners with venom, some making quite outlandish claims and always with a sprinkling of 'i'm offended'. In the red corner: Those who claim that it must be pronounced 'OOK-KUH-LAY-LAY' and in the blue corner, those who claim that it muct be pronounced 'YOO-KUH-LAY-LEE'. Only very recently on a very well known social media group this debate raged YET AGAIN and ran into around a hundred comments.