Although studies show that the legalization of prostitution has some negative social implications, it is unreasonable to make a private interaction between to consenting adults illegal.
There's a service (use your imagination).
There's a certificate of achievement (money) that is used to make a claim on the previously mentioned service.
Theres an exchange of the service for the certificate of achievement.
Don't like it?
Don't buy it.
It's a waste of time, money and resources to try to prevent prostitution. The hubris of Government to believe it can make extinct what's known as "the world's oldest profession."