You can tell this guy has Thailan'd.Thing is, running into someone with a fake ID happens in the US too, and much like in the US, a normal person can usually tell the difference between a child and an adult most of the time. What city are you living in where there's a "very high failure rate" at determining whether or not someone is a child? That's not common.
Out of curiosity, where did you get your Thailand information? Your idea of how sex trafficking commonly works in the big Thailand cities sounds like a really bad Law and Order episode.
The big city bars are not mass renting tired, overworked, underage, sex trafficked women and giving them all fake IDs. Mainly because of the fact that most of the working girls in the large Thailand cities are working by choice which creates a thing called job competition.
The traffickers are spending most of their time sending their victims to less populated areas to work brothels or having them do freelance work. What your claiming definitely does happen, but not nearly as often as you think.