I know that somebody is raping someone in NYC right now and somebody will be killed in Chicago by the end of the day today. Should we ban the cities or at least force them to spend all their budget on security? Or set up curfew for citizens? May be public hanging a la Taliban - those definitely reduce crime.

Humans are using FB and where you have humans they commit crimes. Trying to eradicate all crime when you have humans in the loop is generally not great idea. Besides fighting trafficking/sex slavery with very few exceptions generally means harassing women with zero benefit to society or reduction in actual sex crimes.