Let's start with understanding the term: human trafficking means trade in humans often for the purpose of sexual exploitation or, forced labor. In 2005 global annual profit from human trafficking was estimated for $31.6bn.
I believe that human trafficking is so difficult to stop mostly because of its profitability for traffickers, brothel owners, madams etc. Another factor is social alienation and stigmatisation of victims by society. Governments often do not offer enough support for trafficked victims. Finally, the victims are under huge psychological pressure which is often hard to handle and leads to consequences like learned helplessness or Stockholm syndrome.
The Supreme Court ruled that the evacuation order violated by Korematsu was valid, and it was not necessary to address the constitutional racial discrimination issues in this case.
