Is this not a “double fence” with a no-man’s land in between?
Who would be dumb enough to build a single fence and expect it to actually keep anyone out?
Actually, this episode highlights two sorts of stupidity. First, it shows that a fence is most likely ineffective in the first place, whether single or double. The time required to build an "earthen dirt berm" of the size required to accomplish their tactics was not insignificant: it took hours or even days.
Second, however, despite their obviously enterprising attitude, the stupidity of the smugglers cannot be overstated. If they've got earth-movers big enough to build this berm in a timely manner, why not just use them to drive through the fence?
On second thought, perhaps the smugglers weren't so stupid after all. Nothing better than an eye-catching display like this to distract attention from the real crossing point....
The smugglers know, after all, that it's a lot easier for them to pick their crossing spots, than for the Border Patrol to handle them.
No fence is able to keep a determined person willing to take risks and use ingenuity. Look at the Berlin Wall, people escaped through that death trap right up to it being torn down. Most attempted escapees were caught by the guards, with some killed, with few actually making it.
So, basically, raising the border fence bar (so to speak) to include keeping people out. . .period. . .is unreasonable.