Do you think it's unfair that some people need a visa to travel just because their own country is poor?

My relatives in Vietnam can't visit me in the U. S. without a visa because Vietnam is a developing nation and not on par with the U. S. in terms of economic stability. Now, if my relatives were from South Korea, they could travel to the U. S. whenever the heck they want to, just because SK is a developed nation similar to America. Don't you think it's unfair to restrict people from travelling based on the economy of their country of origin?
Do you think it's unfair that some people need a visa to travel just because their own country is poor?
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