I bet that's it.

I have a difficult time believing that so few were involved. When you consider how many folks work (or perhaps, are present) in each checkpoint and they way the move around, I'd think many more would have to at least be aware of what's going on and if not directly participate, get out of the way to let the meateaters allow the drugs through.

Of course, this makes me question once again why we have a war on drugs.