Its probably not entirely fair distribution you’re seeing.
This starts way back in 1906? A country like China didn’t even have any tech growth till around the year 2000 basically.
They don’t even have an open policy of sharing such things.
Russia did for the longest time, but it’s limited due to the population distribution (basically 80% lives near the western border) so an enormous amount of ground is never watched let alone “stuff” being reported.. let alone that “stuff” getting out to media or the public.
The EU has always had a more open policy regarding UFO’s, especially Belgium shared a lot of footage over the years.
But also much of South America openly shared stuff for the longest time.
It’s only been the USA that turned into a “joke” but due to the paranoia people get whenever a government starts to deny things they first admitted too, people start to report anything and everything.