By Nicholas D. Kristof – The New York Times.

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.

Lloyd is British and the product of a troubled home. As a teenager, she dropped out of school and ended up working as a stripper and prostitute, controlled by a pimp whom she loved in a very complicated way — even though he beat her.

One of the most vexing questions people have is why teenage girls don’t run away more often from pimps who assault them and extract all the money they earn. Lloyd struggles to answer that question about her own past and about the girls she works with today. The answers have to do with lack of self-esteem and lack of alternatives, as well as terror of the pimp and a misplaced love for him.

Jocular references to pimps in popular songs or movies are baffling. They aren’t business partners of teenage girls; they are modern slave drivers. And pimping attracts criminals because it is lucrative and not particularly risky as criminal behavior goes: police arrest the girls, but don’t often go after the pimps. (In fairness, pimping is a tough crime to prove, partly because the star witness is often a girl with a string of prostitution arrests who leaves a poor impression on a jury.)

Eventually, Lloyd did escape her pimp after he nearly killed her, but starting over was tough, and she had trouble fitting in. When she showed up at church in a skirt she liked, four women separately came over to her pew with clothing to cover her legs.

“Apparently skirts need to be longer than your jacket,” she recalls. “Who knew?”

Then Lloyd came to the United States to begin working with troubled teenage girls — and found her calling. In 1998, at the age of 23, she founded GEMS, short for Girls Educational and Mentoring Services, a program for trafficked girls that has won human rights awards and helped pass a landmark anti-trafficking law in New York State. On the side, Lloyd earned a college degree and then a master’s, graduating summa cum laude.

Lloyd’s story is extraordinarily inspiring, as is the work she is doing. One of the girls she rescued from a pimp later graduated from high school as valedictorian. But Lloyd’s memoir is also important for the window it offers into trafficking in this country.

Americans often think that “trafficking” is about Mexican or Korean or Russian women smuggled into brothels in the United States. That happens. But in my years and years of reporting, I’ve found that the biggest trafficking problem involves homegrown American runaways.

Typically, she’s a 13-year-old girl of color from a troubled home who is on bad terms with her mother. Then her mom’s boyfriend hits on her, and she runs away to the bus station, where the only person on the lookout for girls like her is a pimp. He buys her dinner, gives her a place to stay and next thing she knows she’s earning him $1,500 a day.

Lloyd guides us through this world in an unsentimental way that rings pitch perfect with my own reporting. Above all, Lloyd always underscores that these girls aren’t criminals but victims, and she alternately oozes compassion and outrage. One girl she worked with was Nicolette, a 12-year-old in New York City who had a broken rib and burns from a hot iron, presumably from her pimp. Yet Nicolette was convicted of prostitution and sent to a juvenile detention center for a year to learn “moral principles.”

Our system has failed girls like her. The police and prosecutors should focus less on punishing 12-year-old girls and more on their pimps — and, yes, their johns. I hope that Lloyd’s important and compelling book will be a reminder that homegrown American girls are also trafficked, and they deserve sympathy and social services — not handcuffs and juvenile detention.