Democrat politicians have taken an irrational position on the effectiveness of border walls

Ricke Hayes:

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Take the left's view that walls and fences are "medieval" and a thing of the past, and we find, as with many statements made by the left, that the complete opposite is true.

According to a February 2018 American Renaissance article, between 1945 and 1961, over 3.5 million East Germans walked across the unguarded border. When the wall was built, it cut defections by more than 90 percent. When Israel in January 2017 completed improvements to the fence on its border with Egypt to keep out terrorists and African immigrants, it cut illegal immigration to zero. In 2015, The Telegraph reported on the construction of a 600-mile "great wall" border by Saudi Arabia with Iraq to stop Islamic State militants from entering the country. The wall included five layers of fencing with watchtowers, night-vision cameras, and radar cameras. Finally, a September 2016 article in the Washington Post reported on the new construction of a mile-long wall at Calais. "[A]ttacks have considerably changed the climate in France," said Bruno Cautrès, a political analyst at the Center for Political Research at Paris's Sciences Po. "The desire for many is to have a president who can bring security back." The United States has that kind of president in Trump.

So the current trend among modern nations demanding safer environments for their people is not abandoning walls and fences in place of sophisticated surveillance and detection technology, but quite the opposite. In a May 2018 USA Today article, border walls since World War II have increased from 7 to 77. In 2016, the Economist asserted that, as a result of the refugee crisis and the conflict in Ukraine, "Europe will soon have more physical barriers on its national borders than it did during the Cold War."
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There is no rational basis for their opposition to building a border barrier.  The conclusion is obvious that this is a political decision by Democrat politicians not based on fact.