There is a great deal of rubbish talked about prostitution - money for sex - and many misconceptions.
Prostitution is entirely legal in the UK. What is not legal includes soliciting for prostitution, two or more prostitues operating in the same premises (a brothel) or someone other than the prostitute living off the prostitute's earnings.
Prostitution is illegal in Thailand (the country with a sex trade probably only second to the Philippines per capita). In Thailand prostitution is an ancient and not entirely dishonourable profession with an estimated 90% catering for indigenous Thai customers. In the Philippines a greater proportion of the trade is reckoned to be focussed on foreigners (US occupation/bases playing a large part in this).
It is extremely difficult to legislate against the exchange of money (or more properly, money's worth) for sex. The ramifications of this are almost endless.
Some people have no wish to enter into a relationship. They require satisfaction of a basic human need, and are prepared to pay for it. There are many other considerations and discussions to be had, such as the role of purely sexual versus more 'meaningful' relationships, but if one consenting adult is prepared to provide a legal service which the other consenting adult is prepared to pay for, what business is that of anyone else?
Thought for the day: Q: What's the difference between a lawyer and a prostitute? A: There are some things a prostitute won't do for money.