“According to you, why did the Rabbonim make the issurim of yichud, negiah, etc? Why didn’t they “have faith” in the people?”
Are you seriously comparing actual yichud and negiah to people sitting together at a simcha or talking together in the street, at shul, in school, or at a social event of some other type?????
I do not believe this! Maybe according to that way of thinking, a boy should not even be allowed to drive a girl in his car on a date. That is Yichud, too. And she is really at his mercy if the car is on a deserted road. He could drive wherever he wanted. But we trust the boys and the girls not to do anything wrong.