Privacy please

I was just in the bathroom starting the shower for my 9-year-old daughter and she gave me the heave ho. She was like "Mom, I need some privacy please." Great. Fine. But, aren't you the same girl that walked into the bathroom this morning as I was sitting on the toilet and proceeded to have a conversation with me before I could finish using the toilet? Yes, I believe that was you. Why is it that when the door is closed, my children don't think they're supposed to knock. They don't care what I'm doing in there. They just know that they need to be in there with me. I notice kids don't really do that to their fathers. Maybe because they just don't want to be party to what's going on in the bathroom when a man is in there. I don't know. I do know I need a better lock on the bathroom door.