anchor: If you were a photographer and had to hire child models for an important shoot, you could hire from a reputable modeling agency that guaranteed its clients, or you could hire children off the street and also hire an authoritarian nanny to watch them every second.
positive: If you needed children for a photo shoot, you had the choice of a respectable modeling agency or simply picking street kids.
negative: If you were a photographer and need kids for a shoot, your only choice would be to use your own children.