How the heck does an truck load of people cross a border without someone at our border opening the back of the truck and looking? It is a freaking truck, you look.
Checkpoints are too far inland. Those that we have seen and driven through in New Mexico and Texas only have had a couple of employees outside. Everyone we saw, including our van and lots of trucks, was waived through and we have never been stopped even for questioning. There is little or no apprehension attempted in many areas on our southern border.
They probably didn't cross the border in the truck. They crossed with the help of a coyote, were put into a safe house, then picked up by the truck to be transported past the border patrol highway checkpoint.