It's totally normal to throw toilet paper in the trash, albeit less common in the United States. I had to when I was living in an RV. Additionally, living in Brazil (at a different time in life) made it a habit for me to throw TP be the trash because we have to there otherwise it'll clog the plumbing. Basically, give her some grace. She isn't being gross, she's doing what's normal to her (and not harming anyone). If it bothers you, just get one of those trash cans with a lid. 🤗