In America, lay-bys (we call them rest stops) are often a place where prostitution goes on. There is now an organization called Truckers Against Trafficking which encourages truckers to report sex traffic, which often exploits minors and other defenseless people.

Here's their website, which is a real education.

http://www.truckersagainsttrafficking.org/

I have no doubt that this pattern (rest stops and prostitution) is world-wide.

Rumncoke's run-in with a half-naked man very defensive about lights sounds like a run-in with prostitution to me.
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My newspaper ran a story on Truckers Against Trafficking. One day a trucker at a rest stop spotted a woman's face in a trailer window. She looked very pale and sick, and someone inside yanked her away from the window immediately.

The woman had been taken prisoner by two pimps. Among other things, they nailed her feet to the floor. Doctors estimated she had 48 hours to live when the trucker reported seeing her.

It's good to know about; maybe one of us can help somebody someday.