In Germany, the whole world objected to the Russian-built wall that separated families, incited people desperate to escape a communist system to risk their lives to get to the other side, and interrupted commercial exchange. On the Mexico-US border, the two democracies are not at war, at ideological battle, or even economic competition because both economies are intertwined.
If you look closely, you can see the Rio Grande snaking its way to the Gulf of Mexico through the bottom sections of the bars. That's Mexico on the other bank of the river. We've lived with the river and with our neighbors forever and we will continue to despite any man-made barrier.
Yet, there we have it. The Wall. Will the day ever come when people will protest it and move in with sledge hammers like they did in Berlin and demand that it be taken down? Stranger things have happened.)