This is the sad reality about prostitution from the country i have lived in for the past couple years, the Philippines.
There is great misguided misinformation that selling one's body to foreigners in exchange for money pays. For mere reasons that the foreigners currency is higher than the Filipino Peso so they are more likely to be rich or will be more willing to pay more in Pesos as that amount is most likely not as high in their own currency but will make sense if converted to pesos.
This has driven so many people, young and old alike to give their bodies in exchange for cash. It easily feels like the easy way out. Sad part is that even some educated women do this.
This has became such a business that a foreigner does not move freely in the malls, eat freely at a restaurant or even land at the airport single without being approached by a woman/man offering them escort services.
Prostitution is not legalized in this country but somehow people get off the ladder with it as long as they are at legal age. And i am thinking the fact that it helps some people put food on their table for both them and their families, i guess that has contributed to the government being loose about it.
in conclusion i would say Poor "Poverty mentality" is the main cause of all this as these people probably believe only a person from a well off country can get them off poverty and not hard work.
The first thing Is the increase in the wealth gap between the rich and the poor. When society has such inequalities, there would always be an increase of human exploitation.
If the population of the world increases, there will be always scarcity In the number of jobs in the market and increase in the number of people. This job is the most easier to start with no resumes required.
A lot of the population and even people that i know of have to work two jobs to make sure they could make a decent living. I am not sure if it has increased but what I know is that, it is more visible nowadays.
Because human societies are wealthier and wealthier than before. As people have more dispensable income than before, more people can afford to hire services from prostitutes, hence higher demand brought,in higher supply.