Many of the corrupt agents have families on both sides of the border which makes them very approachable by criminal groups with the offer of money. In recent years there has been an even more disturbing trend of cartels finding people with clean records to join BP and OFO specifically to help them get loads across.
No surprise. That's what you get when you want to hire a large number of people and the most important quality is the color of their skin.
It is treason HANG him.
You have nailed the problem. Every barber in a bordertown in Arizona can tell you who is on the take. If you can speak Spanish, and have some guts, a visit to your friendly tavern and $500 will put you in contact with a coyote on the other side willing to do business.