A lot actually. You haven’t been to karaoke bars have you?
I've been to a bunch but mostly here in Japan. The vast majority of ordinary Japanese people can't sing! They sing nasally and not deep from the chest/lungs. Actually, my friend group thinks I'm the best singer which is horrible because I can't sing! I just had a few vocal lessons growing up that taught me to at least summon a voice from the chest/abdomen more than the up high like nasal/throat.
So it's possible I'm easily impressed by Western singers like Ariana Grande. But I watched a bunch of other musical impression vids like that with many other singers and I don't see so many Western singers match that range of vocal abilities.
... lastly, I don't think Ariana Grande is so hot. Maybe a difference between you and me is that I can find girls who seem prettier just walking down the street. But I've never met a girl on the street who can sing better.
Scroll Down to Read Other Opinions