Borders are not meant to keep people out, they're here to keep us in.
Borders are geographic boundaries of political entities or legal jurisdictions, such as governments, sovereign states, federated states, and other subnational entities.
In other words: they are lines on a map. We are born between those lines, and we are taught to believe that we differ from those who are born on the other side of those lines.
However as soon as we grow up and have to find a job, we are confronted with the fact that people all over the world end up working for the same companies. Companies that are not restricted by any borders.
We, the people, are being indoctrinated and are kept imprisoned, making it almost impossible for us to unite. We all firmly believe the fictitious notions of nationalism, cultural identity, money, religion etc. We're all deeply caught up in irrelevant details and this keeps us very busy, and far away from seeing the global picture.
Meanwhile, multinational corporations do unite, with free trade agreements (TAFTA/TTIP, TPP, TISA...), making themselves more powerful than ever...