I think you’re correct. Fencing with sensors in rural areas. Only the sensors shouldn’t be so obvious. A mix of decoy sensors and actual sensors that overlap. Backed up by mobile units. A wall is needed in urban areas, with gates. Barriers channelize traffic. We want to channelize both the people and the merchandise that cross the border to make sure it’s all legal. One more thing: no welfare and no sanctuary cities and no anchor babies. Let’s stop encouraging people to cross the border illegally.
Walls are apolitical and can’t be turned off or left in disrepair.
Too much maintenance. Bad guys will find the weak spots.