Bathroom Privacy Comes with a Cost

Last week I babysat Maya, my usual Thursday morning routine. The reason I'm mentioning this now is because Maya is just over 2 years old, and has recently been potty trained. Needless to say, we spend lots of time in the bathroom.
During our first round on the toilet, she informed me that she needed privacy, so I slid the door shut all but a crack and asked if that was good. "No" she said, "it's not good. All the way". Three and a half minutes later I heard the toilet flush three consecutive times in a row, one after the other, one, two, three.
I opened the door to find Maya standing there, mind you, naked from the waist down peering into the toilet. She looked up at me with her big, blue eyes, pleading for my forgiveness, desperately trying to get rid of the evidence. When I looked down, I saw a clump of tissues floating in the rising water. The box on top of the toilet was empty. I can't get mad at her, because I remember doing stuff like that when I was her age, and, besides, it could have been far worse than tissues. So instead I decided to reason with her, and I explicitly explained to her how tissues cost money, and that it's not good to just throw them away like that, because they're not cheap. That's logical, right? By my reasoning, if she's old enough to request privacy in the bathroom, then she's old enough to understand the value of a dollar.
She blinked up at me and then turned to play in the running water in the sink.

Reminder to self: Only allow a two-year old privacy in the bathroom if she can understand the cost of diminishing returns, monetary value, cash deficit, and price ceilings.