First, I agree with @Ganymede - don't tell someone how to parent their child. You have NO clue what is going on in their world, with their child, etc. Nor do you have a right to know.
Second, it is fucking TERRIFYING raising a child. You are always doing it wrong or not enough. You are too strict or not strict enough. You are surrounded with predators, etc. So as a parent, it is terrifying out there. Completely terrifying. Fight me on this.
Third, no one has to tell you the rules of their household. I'll be honest. Anything with a password, I have that password. If you are my child, I know how to access your shit. You know I will, but I will wait for a reason. Don't give me a reason by showing me that trust can't be given and we are good. I've never had to use a password, but I have them. You don't like that, that's fine. It's not YOUR job to protect my child; it's mine.
My goal as a parent is to have a child that is secure and has the least amount of trauma that I can prevent. I can't prevent it all. They have to make their own choices, but it's my job to guide them. I don't want them in jail and I don't .. let me say this again.. DO NOT want to identify them in a morgue.
So if she needs to protect her child however she feels is right, your job is to shut the fuck up. There isn't abuse. If there was, call a person. Have it checked out. I understand teenagers need space to explore who they are, but they are still very much children. They don't (sorry to any teenagers on here) understand some of the depravity that we do as adults. Honestly, I hope they don't learn about it in an intimate way. I hope they do get their childhood and thank god for people that will protect it.
So TL;DR -- back off of parents just trying to make it so they aren't identifying a body, filing a missing person's, or dealing with a child's trauma at someone else's hands.