But, if one criminal always gets away, I think many criminals will use that as a justification to commit atrocities.
That's why fair assessment is required. And, I personally think US & UK have no rights to teach other about humanity. They are currently pointing atrocities in China to forward their political agenda, not for humanitarian cause. Countries like Sweden & Switzerland are in better position to lecture other other countries regarding peace & harmony.
It's perfectly reasonable. If only some people are allowed to commit crimes, you're not punishing crimes, you're just punishing an underclass. Justice must be blind, or it's just tribalism.
There will always be criminals who get away with crimes, this doesn't mean that we should give up.