Also keep in mind that having a bodyguard many times attracts more attention to you. The vary appearance will lead many to believe you're important/wealthy, and carrying money or jewelry. It doesn't matter how big your bodyguard is (and they don't build them all that big in many impoverished countries) - if a gang of armed bandits stop your car on a deserted road you're probably going to have to part with your cash.

That being said - the one time I've used a driver (not a bodyguard, but a driver who was very familiar with the country and roads) was in El Salvador. I had read that the bus system wasn't particularly safe, as bandits would stop the buses and rob them from time to time. I was on this trip alone, female, and thought it would be good to have someone who knew the roads and the language. I also didn't want to be in a bus without air conditioning in the summer in El Salvador .