>How do you prove your prostitutes are no coerced?

I don't know. How do you prove that any paying job between a paying company and their employees aren't coerced and that the company isn't abusing their employees? As seen with some recent lawsuits, you don't for years until something eventually prompts investigation.

I imagine it's the same here. If it's illegal then the workers have no legal resource and are trapped until someone discovers the company (if ever. Many times these "companies" are just private individuals. i.e. pimps). If it's legal there's at least some chance the worker than defend themself against abuse if contracts are breeched.

> How do you prove that any paying job between a paying company and their employees aren't coerced and that the company isn't abusing their employees?

You can't/don't, but regular jobs are not usually associated with trafficking. And three tends to be less privacy - people don't care as much to file their brothel visits as their cafe visits - wrt regular business, the IRS is known to be formidable if all activity is known about.

> If it's illegal then the workers have no legal resource

prostitution is the job many locals don't want. A similar situation might arise in say, illegals trafficked in and having their passport taken, but this is considered less of an issue do to competition from non-coerced labour, and that labourers are harder to threaten by single "pimps".