The reason this assault reached the headlines was because of the stranger-on-stranger nature of the assault, the fact that it was on the subway in mid-day, and people did nothing. The commonplace sexual assaults involving father on daughter, step-father on step-daughter, husband on wife, teenager on teenager, do not get reported in the news, and they are often horrific. I've had cases where a father raped his daughter from ages 11-16 at least 1x a week and gave her HIV and was training the 5 y/o; father on 6 y/o daughter for months and she outcried in her classroom when the teacher asked the class to draw a picture of nighttime and she drew a picture of him sodomizing her in the bath; girls who physically could not move their mouths to speak about what their step-dad did and the only evidence we had was DNA; it goes on. And these are just the reported cases. Because the perpetrator is often in a position of power over the girl., she often does not report the events. Thus, many cases LE never finds out about.
In fairness to Chris but not to take away from your point, what I just described may happen in the country with the same frequency.