As long as we pretend to be soverign and allow MILLIONS of Mexicans to enter our country illegally, there are no rules to this game.
The fight isn't about anything more than the access to moving drugs across the border at Nuevous Laredo. Money, money and more money = fight to keep it. There is probably 5000 semi trailers a day that are moved either with tractors or by trains across that POE.
We probably have enough corrupt Border Patrol Agents in that one POE to supply the UN worldwide. Just the enormity of vehicles being moved everyday makes the job of inspections almost impossible. What an ideal situation for drug dealers.
If citizen groups started following some of these higher ranking agents home at the end of their shift they would more than likely find themselves in the best part of town where everyones wife drives a $50,000+ vehicle and has two maids.