Was it for money, because they felt unappreciated, because they saw too many bad things and just stopped caring (or were ordered to do said bad things and it broke them), because they didn't care in the first place and enrolled just to get the training?
The situation is certainly quite bad, but understanding why it got there in the first place could be interesting, if only to protect other countries from the same experience - ie a drug startup could consider setting shop in, say Canada, with a much larger and far less controlled border, lots of empty space and forest to run labs (etc) using the very same methods.
Reservations, crime and drug friendly cities like Winnipeg could offer them a great advantage - or if we talk about geography, sea access from Labrador to the European market could also be an advantage.
So the question is - why did it happen in Mexico?