Run-away children and the Austrian house of horrors

Out of morbid curiosity I was reading an article in the Guardian about the latest Austrian dungeon horror story, and I came across this shocking bit in the middle of the pretty long article. I've read a few articles about this before, and I've near heard this mentioned.

Though domineering and despotic with all his children, Fritzl appeared to treat Elisabeth even more brutally than her siblings and Hoerer got the impression that 'he did not like her very much'. When she reached the age of 11, the abuse started. From then on Elisabeth would be raped by her father regularly: in his car, during forest walks, even in the same cellar that would become her prison.

At 16, she twice attempted to run away from home, but each time was delivered back into her father's violent embrace by the local authorities. Three years later, there was no possibility of escape.

It's likely that she didn't tell them that her father had been raping her, but even so, shouldn't a 16-year-old girl be old enough to decide whether or not she wants to live with her parents?