>Contrary to popular belief, the United States does not require police officers to identify themselves as police in the case of a sting or other undercover work, and police officers may lie when engaged in such work. The law of entrapment instead focuses on whether people were enticed to commit crimes they would not have otherwise considered in the normal course of events.

--your source

Not as straightforward as you're implying.

Now tell my how pretending to be a 12 year old girl forces somebody to commit a crime?

Forcing somebody isn’t entrapment. Entrapment is providing opportunity to encourage someone to commit a crime that they might otherwise have not committed.

Then tell my how pretending to be a 12 year old girl encourages somebody to commit a crime?