While that is true in many cases, in many others it is not. I lived on a border town for a few years and made friends with some DHS agents there. Listening to their stories re drug trade I got the impression that many of the people carrying drugs over are actually poor, uneducated, uninformed, etc. While some of the techniques may be sophisticated, I got the impression that the traffickers themselves frequently were not. I would imagine basic abrasive interrogation techniques would be reasonably effective.