But what you are seeing is the same results of what happens when the government controls the wealth in a country.
I'm not sure it's that simple, though you do have a partial point.
Having spent a lot of time there, I can assure you that best description of Cambodia's government is "warlord kleptocracy". It isn't even close to being communist.
Yes, wealth is in the hands of the warlords, and they will do just about anything to get it: brothels, heroin trafficking, arms sales (almost openly and to the Tamil Tigers when I was there), and plain old graft and payola.
That's all an effect of the warlord society, and Cambodia is a nation of warriors, no ifs, ands, or buts.
Ironically, Nepal is having a true Maoist Communist insurrection which is aimed at the (also kleptocratic) Rana monarchy. And Nepal also has (or had) several "brothel towns" which were exclusively the domain of Nepalis and Indian traders. No Westerners, not one. They weren't allowed there. Despite those "brothel towns", there is no sex tourism in Nepal. Same in Delhi and Bombay.
The myth that Westerners are responsible for Asian prostitution is absolutely ludicrous and bizarre, though Americans are ignorant and naive enough to believe it. It starts with the locals.