MLK said something along the lines of, there is no problem with just laws (such as those upholding border security), but there is a problem when they’re applied unjustly.
There is nothing wrong, all other things being equal, with enforcing border security. I think this is where your perspective comes from. Nations have sovereignty. Therefore, they can enforce their borders. If all else actually was equal, it would be a sensible argument.
However, this new “virtual border fence” does not exist in a vacuum. The current administration - and the prior administration - has ramped up immigration enforcement efforts, in many cases tearing apart families who have lived in the U.S. for many years, had kids, jobs, etc., causing immense pain. Billions and billions spent to remove hardworking residents from the country and place them back across an imaginary line. Why? Because “law and order”. How will your children sleep, if an illegal immigrant is working night shifts to send money back home to his struggling family? The response (e.g. ICE raids, children in prison camps separated from parents without medical care/showers/hygiene, increased enforcement causing more dangerous crossings resulting in drowning) is clearly disproportional to the crime, even if you see illegal immigration as criminal and unjust. The “virtual fence” exists in context with all of these other realities. Perhaps you can see why myself and the parent commenter aren’t exactly cheery about our nation’s innovative, synergistic solution to border enforcement. All of the unjust measures mentioned above (minus perhaps more ICE raids) will be easier than ever to do. “How beauteous mankind is! O brave new world / with such efficient surveillance measures in ‘t!”
Even if you see the startling conditions/extensive surveillance measures as justified and deserved of people thrust into difficult circumstances beyond their control, the current administration is clearly incompetent and untrustworthy in the task of implementing such a border fence system. Do we really trust the people who separated parents and children without keeping track of which child belongs to which parents will use such a system in a just manner? I seriously doubt it, and therefore I doubt any argument implying that all enforcement measures can be justified because “order”. Breaking the law does not make you subhuman, and no new measure exists in a theoretical vacuum of just intentions.