The facilities aren't even remotely hidden so it's fair to blame Cambodia for allowing it. They have towns built up around them with restaurants and shops and normal economic functions to support the people running these slave towers. A good chunk of the money is flowing back into China, but there's definitely a good bit that seeps out into the Cambodian economy. Hence why Cambodia's government is more than happy to let it operate.

In the case of Myanmar, I think their biggest problem is the country has been in a war for decades with loads of various factions and it's too chaotic for any government to attempt to get anything under control.

Yes a huge chunk of the blame falls on Cambodia, Laos, Myanmar, etc

And bordering countries like Thailand are running into issues where people are getting trafficked through Thailand to these other countries. So it's actually ruining the reputation of Thailand and lots of Chinese people are wary of traveling to Thailand because of it

To provide a bit more context what happens is Chinese people will give fake job offers to their fellow Chinese and then basically kidnap them when they arrive to Thailand and take them to another country to work in a scam center