Laws are part of the super-structure not the base of society and using laws to minimise harm, either legalisation or in criminalisation of buyer/sellers is not the answer when you overlook the economic structure.
It's no use having laws and exit programmes when there is an ever increasing pool of forced labour or poverty stricken women being poured into the industry everyday.
Only educating women, ensuring access to (free) higher education, free childcare, better support for single mothers, access to affordable quality housing, forcing employers to pay a living wage, predistribution of wealth, ensuring that women on lower wages are able to take maternity leave etc & raising aspiration has any hope of freeing women.
I like what Alexandra Kollontai a real revolutionary had to say on the matter in 1922 
"The hypocritical morality of bourgeois society encourages prostitution by the structure of its exploitative economy, while at the same time mercilessly covering with contempt any girl or woman who is forced to take this path"
"It is also significant that in the capitalist countries prostitution recruits its servants from the propertyless sections of the population. Low-paid work, homelessness, acute poverty and the need to support younger brothers and sisters: these are the factors that produce the largest percentage of prostitutes. If the bourgeois theories about the corrupt and criminal disposition were true, then all classes of the population ought to contribute equally to prostitution. There ought to he the same proportion of corrupt women among the rich as among the poor. [insert, if it were really a choice ???] But professional prostitutes, women who live by their bodies, are with rare exceptions recruited from the poorer classes. Poverty, hunger, deprivation and the glaring social inequalities that are the basis of the bourgeois system drive these women to prostitution"
Nothing much has changed in nearly 100 years but then we have had capitalism for some 250 yrs. Which rather makes the case that nothing can and will improve under capitalism.