Wrong answer in MHO opinion. The maybe easy answer is that said waitress has an abusive boy friend or husband. But its not always true because sometimes such injuries can also be inflicted by accidental circumstances.
Something that actually happened to the family of an ex landlord of mine. Who had to endure end less grief from child welfare folks when such a injury happened to their daughter that was quite accidental.
Or I could talk about me, when my wife and I were rear ended by a drunk driver. In my wife's case, her injures were not publicly visible, but anyone viewing her tits could easily assume I had been using her tits as punching bags. And it took many weeks for the bruises to finally heal.