When we hear about human trafficking in India or Cambodia, our hearts melt. The victim has sometimes been kidnapped and imprisoned, even caged, in a way that conjures our images of slavery.

But in the United States we see girls all the time who have been trafficked — and our hearts harden. The problem is that these girls aren’t locked in cages. Rather, they’re often runaways out on the street wearing short skirts or busting out of low-cut tops, and many Americans perceive them not as trafficking victims but as miscreants who have chosen their way of life. So even when they’re 14 years old, we often arrest and prosecute them — even as the trafficker goes free.

In fact, human trafficking is more similar in America and Cambodia than we would like to admit. Teenage girls on American streets may appear to be selling sex voluntarily, but they’re often utterly controlled by violent pimps who take every penny they earn.

From johns to judges, Americans often suffer from a profound misunderstanding of how teenage prostitution actually works — and fail to appreciate that it’s one of our country’s biggest human rights problems. Fortunately, a terrific new book called “Girls Like Us,” by Rachel Lloyd, herself a trafficking survivor, illuminates the complexities of the sex industry.