As can be seen by inspecting the fence, it was always very easy to cut through the fence. Illegal immigrants could easily get past the border. A fence or wall large enough to keep illegal immigrants out would be extremely expensive. Instead, drones should patrol the area and shoot down any illegal immigrants from the air.
As long as there is a demand for black market labor in this country (i.e., labor for less than the prevailing minimum wage or labor in an illegal enterprise such as drug trafficking), superficial remedial "solutions" will be worthless. People will find new ways to get into America, fence or not.