The thing that worked against Tiffany the most, IMO, was going missing from 'no fixed address'. We can thank the fact that she had an online presence for the rapid discovery of where she had actually been that day. Without that, she would have completely been dust in the wind. Rather than to judge her (however, I DO have issues with her partner) we should question the values our popular media put upon our youth, particularly the early sexualisation of girls. I know I'm not saying anything new.
It is quite likely in the absence of school attendance, and her mother, Tiffany's world view came from her partner and the television. Her father's suicide and subsequent absence from her life from age five must have been very difficult for her, perhaps giving her a need to nurture an older man from an age as young as 12 (who lavished attention on her).