There has been a dramatic increase in private security firms in Mexico in response to the infamous Mexican cartels turn their attention to kidnappings and ransoms. The cartels are targeting middle and upper class citizens, which exacerbated the need for private security in addition to already overwhelmed police and military forces. While this has increased safety for Mexico's upper class, it has diverted resources from the country's significantly larger poorer population. In addition to this, corruption, and unlicensed companies are rampant.
The whole article provides excellent insight into the challenges of private security firms operating in countries with rampant social inequality, well armed criminals, and rampant corruption at the local, state, and federal level.
Source: Duncan Tucker, Al Jazeera