It was reported in the very first paragraph of the article and in countless other articles the past few years: these people are kidnapped and kept as slaves. Nobody decided "yep, I want to get kidnapped during my relaxing trip to Thailand and be transported to the Laos/Myanmar border to be beaten half to death and take on call center work with the risk of being murdered should I refuse."

Because that is what is happening. People who get kidnapped and refuse to work are being murdered. This isn't call center work. Some people may be doing this voluntarily around the world, but this article is specifically about people who are being held as literal slaves with zero chance of walking out alive on their own free will. And it's worsened by the fact the governments of Laos, Cambodia, Myanmar (or what's left of their government), and Thailand are all complicit in this. It brings in big bucks, and there are reports of police even bringing people back to the compounds if they somehow escape.