Sure, going elswhere is something you can do, if you can afford it. But:
A) There are societies, in which the circumstances which would make it reasonable for you to leave are the reason why you cannot. E.g. if you are living in slavery or quasi-slavery moving somewhere else would be good, but the ones profiting from your labour wouldn't like that, so they make it hard. And the reason why you ended up in that position e.g. lack of funds, lack of education might also make it hard or impossible to move somewhere else.
B) We are discussing human rights. I would think they should apply universally. That is of course not the reality of the world, but we should aim for those rights to be defended in each part of the world.
Human rights are a thing that has to be defended by those that are able defend them — and those people are typically not the victim of such violations, but precisely the opposite in terms of social, economic and education capital than the people that would benefit from moving away.
That means just move away as an answer from the standpoint of the affected people is just profoundly naive, as if one would say to "just get rich" when someone isn't or "just get healthy" when someone is ill. On top of that it is an answer that hurts the society of those that give it, as the society as a while accumulates injustices it fails to answer.
So why give thwt answer? Because it has one benefit: It is a simple cure for the nagging feeling of cognitive dissonance that each good person has to get, when they see that the society they are part of produces injustices. It is the answer that allows them to move on and change nothing. "It must be their own fault then".