It's probably true that real people cost less, but for some sort of image it may be a little time consuming to find a real person willing to do that which you want to show. Even on that den of depravity known as the Internet. Which explains certain Poser sites it is not compatible with the TOS to name. Mostly filled with awkwardly-posed Vickies with the same expressionless face. Personally, I reckon that even the pictures of real humans can look a little contrived.