Is there a non-emotional or moralistic argument for why prostitution should be illegal? What is actually the harm, and is it worse than the black market for illegal sex work?
There is at least one such argument: prostitution as a crime of danger. I try to articulate it below.
Prostitution by itself is not wrong, but the social dynamics around it put the prostitutes in a weak position, in which they are at high risk of abuse and exploitation. Under this interpretation, prohibiting prostitution harms the few prostitutes which would mot be abused and their clients, but benefits the majority of prostitutes who would be abused and is overall positive for society.
The logical structure of the argument is sound. As a society, we regularly accept to forbid behavior that is not necessarily harmful, but has an very high risk to be, and a limited social value if allowed. Gun laws, speed limits, age of consent laws follow this principle. [Aside: the social benefits of gun ownership are valued more in the US than in Europe, therefore gun laws are more permissive]
There are however at least three problems with this argument:
1. It supports punishing pimps and clients, not the prostitutes themselves. This is in fact the approach chisn by e.g. France and Sweden, but not by the US.
1. It assumes that a substantial proportion of prostitutes are exploited or abused and that there are no alternative policies to prevent this.
3. It ignores second order effects. It assumes that forbidding prostitution will eliminate it and doesn’t consider the additional risk of harm resulting from pushing prostitution to the black market.
Seems like all the risks you just associated with not-prohibiting prostitution would also apply to farming. Given its deplorable history in the US vis-a-vis slavery, it seems to be we can’t possibly risk more individuals being exploited in such a manner. Granted I’d concede that farming has substantial benefits, but frankly so does sex to those who cannot obtain it socially. Arguably the need for sex is tantamount to the need for food itself.
If people cares as much about the safety of people working on farms as they pretend to care about the safety of sex workers, farms would've been banned a long time ago. There's a lot of people working a lot of hours for little money under bad circumstances on a lot of farms.
That doesn't mean all farms are bad, but many of the same dangers do exist to the workers down the chain and regulation seems to avoid having to raise prices more than protect workers.
In my opinion, political opposition of the basic concept of sex work is all about politicians' personal morals and a lot of fear mongering to convince the masses of their point of view.
For farms, the social benefits of having farms are arguably higher. Hence the government tries alternative approaches, i.e. labor laws. Admittedly, the government is not enforcing labor laws effective ly, but the reasons are beyond the scope of my answer.
> 3. It ignores second order effects. It assumes that forbidding prostitution will eliminate it and doesn’t consider the additional risk of harm resulting from pushing prostitution to the black market.
At it's heart this is an argument of pragmatism, but it is never checked to see if it actually works.
Like many prohibitions, the negative unintended consequences are worse than than the original problem they purport, but entirely fail to fix.
Wiki lists some, with sources for further reading. Most prominent non-emotional argument seems to be that legalizing increases demand, meanwhile many would remain illegal nevertheless - so the related crimes' prevalence would increase.
Health and safety requirements. If testing and contact tracing isn't properly done it can be a problem, but as you said is it worse than black market conditions with zero oversight and safety stands? Probably not. The real risk is a lack of health insurance, retirement benefits, and taxable wage by allowing the black market conditions to exist. From a problematic standpoint is the "hostile work environment" claims if sex workers become legitimate.
Not that I buy into the argument but that it helps to create more human trafficking and the involuntary part of the trade has a better hiding behind the legal one.
It seems that some people do, in fact, sell consent. I know for the right price I'd sell my consent. And I don't buy into the premise that prostitution cannot exist if we want to reduce objectification.
