The truth is that they can set up a any of several types of detection systems that would inform agents when the first wall was breached. By the time they got over the second wall then the agents could be waiting to pick them up. The truth is that those that are leading our country have reasons why they don't want to stop illegal immigration. They do not love America at all. They hate it. We need to start replacing them with people who do love America, or it will be destroyed.
Without first over whelming the USA with a illiterate majority, the new world order will never happen. Both parties want it to happen. Neither gives a damn what we want.