Large shipments quite literally rely on small individuals being busted. For at least ten years now, border security agencies have been receiving training on how not to act in the face of a small bust. Their typical response is to start waving people through with little to no scrutiny, because all of the agents want to have some part in the bust, if at least just to have a rubbernecked sort of view at the excitement going on. Now they are being trained that the presence of a small bust is the cue to start raising scrutiny on all vehicles, and larger vehicles in particular.
One of the most disturbing findings is that the largest busts are almost always precipitated by some individual getting caught who is absolutely insistent that they didn't know that a brick of coke was taped to their gas tank (or similar). Previously, those individuals might go straight to prison for a decade or more on trafficking charges. Now that agencies (and defense lawyers) are catching on, there is now a lot of credence given to the idea that those individuals are actually unwitting drug mules used to distract CBP agents from doing their jobs while they slip truckloads past them at the border.
How many "drug traffickers" have we imprisoned that have merely been pawns in a drug trafficking scheme that they had no part in?