Ludwig von Mises, in his The Clash of Group Interests published in 1945, looks at open borders as if the only issue revolved around economic returns. It is over the question of open borders that the left and right completely coalesce. It is where grand theory utterly obliterates reality and common sense. Australia and New Zealand, in the passage below, are mere examples, the best he could find at the time. Today it is the United States and Europe, to the extent that anything is left of their original structures, that are specifically under assault by such thoughts.
The root causes of present-day group antagonisms must be seen in the fact that we are on the point of going back to a system of rigid castes. Australia and New Zealand are democratic countries. If we overlook the fact that their domestic policies are breeding domestic pressure groups fighting one another, we could say that they have built up homogeneous societies with equality under the law. But under their immigration laws, barring access not only to colored but no less to white immigrants, they have integrated their whole citizenry into a privileged caste. Their citizens are in a position to work under conditions safeguarding a higher productivity of the individual’s work and thereby higher wages. The nonadmitted foreign workers and farmers are excluded from enjoyment of such opportunities.
I don’t know what can any longer be done about such stupidity other than to recognise that there it is, and take the appropriate actions to save what you can while you can.