1. Alcohol clouded judgment.
2. Spiked drink.
3. Naive judgment. Thinking she's safe with friends, but going away with someone strange anyway. I just saw a picture of one of the suspects on FOX NEWS. He was a black male. Years ago I read of a black convict who would attend parties and he and his buddies would hit on a white girl and try to convince her to ride with them when they went for some more liquor. If she hesitated they would work on her conscience with hints that she is racist. When she gave in and went with them they would rape and sodomize her.
Boy, things don't change much. I knew of black guys who would come down from Detroit to Ann Arbor in the '70s. They would target white college coeds and play the same game. No one I knew wound up dead, but one did get beat up and several got taken for money, cars, a free place to stay (which was the intent of the scam) for months until they wised up.
I'm black and I could tell these scam artists a mile off, but these white girls seemed blind to the obvious. It's not that I was more sophisticated than they, but at least my lawyer father warned me before I left home as to what people will do to part you from your money or your underwear.