it could happen but only with a global communist police state, borders are then not between countries but between individuals and their access to consumption capacities. and socioeconomic structures.
The idea of an open border is to remove those very limitations and consumption caps. Why should you deserve more food and a better lifestyle just because you happen to be born at a certain geographical location? What makes you the better human?
Here I say you I mean everyone who is from a wealthy first world nation.
Even the term first world is derogatory, seeming like you belong to an alien planet and not earth. Makes no sense.
no one prevents the citizens from the poorer locations to enrich themselves through work, why steal from others, that sacrifice themselves in their work?
check soviet russia society, there you will see inequality comes back even if all are equal.
in a global communist state, there will be again capitalists arising out of common consensus and those will be privilegedly threated, even if they are not claim themselves being appointed by gods etc.