My argument is, and remains, that children do not have a right, to privacy. Sure, perhaps they will earn more privacy as they demonstrate the ability to make increasingly wise decisions, but it should (and does, in my house) remain a privilege - and one that can be removed at a moment's notice should I as the parent feel it necessary for any reason.
Even if your kid is a straight A student who stays out of trouble and volunteers her free time at the nursing home, it is still possible for her to get suckered by some jackass into doing things that she shouldn't do - things that aren't even obvious to some adults that you shouldn't do, such as giving out personal information on the internet. So yes, if I had a teenaged daughter I would want to know what she was doing on Myspace (and not just because no one uses myspace anymore
), facebook, hell, even something silly like second life.
The internet is not the forest of fear that the media makes it out to be, where any woman who ventures online will end up getting raped and having their identity stolen. But it is also not happy playland either. The anonymity of the net encourages people to be their true assholish self. Sometimes this manifests as something benign, like being more blunt on a message board than they would in real life (that would be me,) and sometimes it manifests as a fetishist who likes to see how far he can get a teen girl to go sexually, or if he can get enough of the kid's information to steal their identity.
My job as parent is not only to raise my kid to eventually be a self-actualized adult, but to also protect them from dangers of which they have no experience, while remaining fully cognizant of the fact that teenagers as a whole feel themselves to be immortal and invulnerable, until something bad happens to them.
I have no problem with authoritative parenting. I think it better by far, in fact, than authoritarian. But an authoritative parent does not claim that his kid has a right to privacy. That is the claim of the laissez-faire parent, and I will firmly tell you all day long that such a parenting style is detrimental to the child, both from a safety standpoint as we are discussing here, and from a growing-into-a-mature-adult standpoint.