Is the harlot a essential "job" in the world?

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I have heard that in the 1980's, in China, a woman walking alone at night would be very dangerous. Because she could be running a risk of being seducing. But now the surroundings are much better now, for there are many night walkers. And the night walkers are also beneficial to the development of the country. Many people believe that night walkers are essential to the the society. I want to know what is your opinion?