To be specific, my application field is physics. And I am from a country where students are aggressive on standardized tests like gre's since we put much emphasis on training for these tests. I was talking with peers about whether to send my Physics GRE score to my target physics schools which is 800/990(67%) as a computer science undergrad student, and they told me don't do it because, given my nationality, admission committees will set a higher bar for me and a percentile below 85% is a minus. That arose the question in my mind that I know it's normal that in US graduate admission process, admission standards for international students are set higher than those for domestic students, but do graduate admission committee View International Applicants country-wise? I asked my peers about this, and they say that's a widely accepted speculation among them, so I am asking here to verify.
I doubt that there is any widespread effect of this. In fact, most grad schools would want, and many would require, a "level playing field" for admissions. But the GRE is not the main determinant of anyone's admission. It is at most an indicator, among many others, that might indicate success in a program, or not. Letters of Recommendation are relatively important in US.
Your application needs to give strong indicators of your likely success. But you don't need to be "perfect in every way" to gain admission.
do graduate admission committee View International Applicants country-wise?
Mostly no. US physicists do not care about your nationality. They just want PhD students who produce good publications.
The people who issue student visas care about your nationality. If you can't be a good PhD student because you cannot get a visa because of your nationality, you may get fewer PhD offers from the US. This is why Canada has so many more Iranian physics PhD students than the US.
Some places don't mind if nearly all their students are Chinese.