The answer to this is no. Walls do have a history of doing their job and, indeed, they are the tried-and-true go-to strategy almost everywhere that security or illegal migration is a concern ... So, let's consider the precedent of walls and systems designed to maintain security and keep illegal immigrants and terrorists out while allowing legal immigrants and visitors in:
Consider first buildings like the White House, where a decorative fence predated the wrought iron fence installed by President Ulysses Grant to control New Year's crowds. President Franklin Roosevelt began restricting access to White House grounds to appointment-holders only during World War II as a further security measure.
But the White House is a building and different than a national border, even if the logic remains the same. Is there a precedent with border walls working along much longer distances?
Here, again, the answer is yes. Consider the following: