Agreed.
However, one country's human rights violations is another country's normal way of life.
Mick Jagger back in 1967 after a drugs bust saying to a judge (?) when questioned about his way of life - "You have your morals and I have mine".
I agree, moral and ethical comparisons can and often are rather subjective dependant on the culture and/or individual.
However, I believe there are way's to remove some of the subjectivity and create benchmarks and baselines for human beings as a whole.
Firstly, one compare all the nations and establish the mode, median and mean for various aspects of human rights and behaviour as well as an over all baseline.
At the very least, that would allow anyone to point out nations or individuals who fell well below the average in their treatment of others to be in moral deficit in contrast to the majority of humanity.
The second option is to discard opinion altogether and attempt to scientifically establish a baseline of welfare for human beings based upon the needs of the individual and in societies.
We could establish and differentiate between what people perceive as threats to their safety and welbeing against the evidence to at least inform us of whether a particular moral or ethical stance is reasonable or a prejudice.
For example, it is probably quite reasonable to assume that being the victim of theft is damaging to the individual and fair to say that the thief is acting immorally.
However, is there any evidence that seeing two people kissing in public actually causes any harm to those that witness it.
There are always going to be grey areas, but we can at least set the boundaries on the extremes and continually work towards refining the picture.