Go to China and the level of ambient noise is much higher, whether that is people talking louder or having no qualms playing music from their phone speakers at any time of the day.
So at a guess, I think that cultural conditions probably lend themselves to people of Asian heritage learning to sleep under noisier conditions. Of course, these are all anecdata and generalisations so ymmv - fwiw, my personal observations are somewhat in line with yours.
Personal anecdote: when I grew up my parents lived on a busy main road so I was used to sleeping in noisy conditions. I then moved to a quiet village - I love how silent it is on a night - but I now cannot sleep in hotels nor anywhere else unless it's absolutely silent.
They say in the army, your survival is predicated on being able to catch a wink wherever possible.
As for sleeping in quiet places, one thing I've noticed is that my tinnitus is only audible when I am not in a city, as such there have been times where I remember I have tinnitus and am temporarily unable to sleep because of it.
I find it to be very curious how in one country, blasting music at 3am on a train is fair game, while just a stone's throw away over the pond it is a social faux pas to have your mobile phone ring on public transport, let alone answer the call...
That would prove to be an interesting "control" but I have less anecdata to draw from there...