Should prostitution be cartelized?

What else does one ponder in Amsterdam?  Majkthise says yes, prostitution should be cartelized:

It is important to legalize and regulate the sex trade in ways that enhance the autonomy of sex workers. There are many good reasons not to let sex work become another service sector job.

It seems only fair that the world's oldest profession should be granted the legal status of other self-regulating profession. Sex workers should have professional organizations that license and certify members according to the standards of their peers. Doctors and lawyers have a similarly sweet deal in which the state agrees to impose a monopoly on the supply of healers and advocates in exchange for quality assurance. If the law said that you had to be a registered member of your State Prostitute's Guild in order to legally sell sex, then only people who actively sought to qualify themselves would be eligible to work as prostitutes.

I see two paths.  The first is an anti-egalitarian premise.  "It is only the politically connected prostitutes we should care about.  They will bring prostitution to a higher art form and lead better lives." 

Second, prostitution as an occupation, might be subject to crowding costs.  In that case a tax or quantity restriction can improve matters, just as a toll on a busy road might decrease congestion by pushing people toward less crowded routes (average vs. marginal values).

The argument must be that as prostitute wages fall, the sector brings more abductions and beatings.  Perhaps the lower wage attracts the legally helpless.  For this effect to imply the efficiency of cartelization, the worsening of treatment must be stronger in the sex industry than in the other sectors "marginal prostitutes" might work in. 

I worry about the secondary consequences of cartelization.  Cartelization creates supra-normal profits for illegal entrants; this encourages the very kinds of illegal and oppressive behavior that cartelization was designed to prevent.

I wish to legalize prostitution, not cartelize it.  But it is tricky.  Communities should zone prostitution out of most areas, and that will limit supply.  Even minimal health regulations on prostitutes will limit supply as well.  Partial cartelization is probably part of a good solution, but that is distinct from seeking cartelization for its own sake.

Please note this is not a post about immigration; for the purposes of argument take the number of women in a country as given. 

As for zoning, had I mentioned that in Amsterdam one can find a kindergarten right between two open-window whorehouses?  I was told by one woman that this is "not a problem."  She was, however, a former prostitute and perhaps not a credible source; she may have been concerned with the Pigouvian definition of externalities (the externality runs one way only) at the expense of the Coasean definition (consider the effects on all relevant parties).

In Amsterdam (I am told), twenty minutes in the red light district costs 30 to 50 Euros.  I wonder how close that is to an optimal degree of cartelization?

Addendum: How is this for a bizarre sentence?

In the year 2000, the Dutch Ministry of Justice argued for a legal quota of foreign sex workers, because the Dutch prostitution market demands a variety of bodies (Dutting, 2001: 16).  [Source here]

That is one of the most er...creative arguments for protectionism I have heard...

Second addendum: Here is a fascinating article about French policy.