I'm hesitating for a moment because there are many different models and approaches to regulating sex work in different areas across the globe. I will say that some of the models, like those to which you're referring, are what can generally be called legalized models. Legalized models create very strict and limited circumstances under which certain people are able to work, as opposed to, say, the model in New Zealand, whereby it's not about creating really oppressive conditions; it's about removing the criminal law and allowing existing employment, occupational health and safety, and public health laws to come into play instead.
Any legal model needs to be tailored to a particular legal context and to a particular country. What may or may not work in Germany, for example, may or may not work here. Part of the problem, though, is that there is a conflation of trafficking with sex work, and then when one tries to address both of them together, one ends up with sometimes disastrous outcomes.