Because tooth fairies only want milk teeth that have fallen out naturally and is given willingly. If it started graverobbing dead people or knocking out adult’s teeth when they are sleeping, they would lose their ability to fly and they would become a dark shadow creature, alone and hiding from the light of day. And tooth fairies love the sun and they love the smile on children’s faces when they lift their pillows in the morning to see what the tooth fairy left them. That is what makes them fly and what makes their stomachs tickle with happiness.
And that is why tooth fairies don’t rob graves.
If you were concerned, then why not send a private message instead? “Not trying to be rude”, sure. Sounds like you’re trying to intimidate. Maybe you shouldn’t do that.