Really? It is quite common these days to have parents who don't take very good care of their kids. I had two parents, but I ran wild and they never knew (or cared) where I was or what I was doing.
Then the author should clarify that, I suppose.
But if you have a twelve year old protagonist, for example, and they're running off to who knows where for an extended adventure, it is a bit silly not to address it. Only the most negligent parents aren't going to be concerned at that age after an evening goes by, and pretty soon you'd have the authorities involved and everything else.