In New Zealand, prostitution was legalised eight years ago, and before then the authorities turned a blind eye to it. The ostensible reason for legalisation was to protect the women involved, and to regulate and tax the industry. Although MPs were given a free vote, I understand the Prime Minister at the time (Helen Clark) let it be known quietly that she supported legalisation.
Most articulate groups favoured prostition (ie, the Prostitutes' Collective, feminists and even the more liberal element in the churches). The prevailing view was in my view oversimplified, ie, a consenting non-coerced adult had the right to sell sexual services if (s)he chose. Questions as to whether this is the way the industry would operate if legalised were not really considered: it was assumed that once legalised, the criminality and coercion would wither.
A review a few years later concluded that a) there had been no increase in prostitution (contrary to fears) and b) there was no evidence of trafficking. Rather obtusely, this review did not cover prostitutes who did not have English as their first language. I'm sure I don't need to explain why I think this was obtuse.
There have been complaints by NZ prostitutes that they are being undercut by unlicensed brothels operated by people from abroad: there are further anecdotes concerning how organised crime (also from abroad) operate these businesses.
The main street in my town contains two places that are pretty obviously brothels (ie, they advertise "massage and escorts"). One is right on the corner of the town square. It is quite a seedy-looking place from the outside (and in case anyone wonders, I have not seen the inside).
None of my friends have admitted to visiting prostitutes, although there are a few who I think probably have. There is still a stigma about doing so. The general impression is that men who visit prostitutes do so because they can: it is not really very different from picking up someone in a bar for a one-night stand, except that they don't pay for the drinks. A lot of the motives stated in this discussion above would be considered by most people down here to be overthinking. The presumption about Antipodean men tends to be that they are unreconstructed red-blooded men; they will ogle women, they will go to strip clubs etc, and the women tend to accept to a greater extent than I think women would in other parts of the developed world.
To my mind, legalisation has not made much difference: prior to legalisation, there were places in the dodgier parts of town that advertised "massage and escorts", and most broadsheet newspapers carried advertisements for prostitutes as they still do. I suspect that despite legalisation, a fair amount of the sex industry remains underground because it is more profitable that way and there is exploitation. The problem is that no one is investigating these issues, leastways not publically.