Well, many Chinese museums 'matter-of-factly' display artifacts plundered from their subjugated populations (the Uighers, the Tibetans, the Miao, etc) so I'd hazard a guess that it's a fairly universal trait.
I have been to many major memuems in China and I don't remember seeing large sections of precious artifacts from the populations you mentioned. Can you name some of them? Also technically they are all within one country, it's different from what we are talk about.
Technically Greece and Britain are within the EU.
No problems there either.
Just renamed the British Museum the EU museum and we are fine.