These stories come as no surprise to me. People today have an "If it's free, it's for me" attitude. And if it's sitting still, and nobody is looking, they think it's free.
Someone at work used to steal lunches all the time, particularly my friend, David's. One day he deliberately put a cat food sandwich in a lunch bag, with his name on it. Of course, it was stolen. The next day, the note read:
"Thank you for eating my lunch yesterday. I hope you enjoyed the cat food sandwich. May your coat glisten and your eyes shine. And may you get the unabating urge to scratch up your furniture and puke hairballs all over your bed. Signed - David."
Although the lunches continued to be stolen (yes, the perp was found to be the junkie brother of one of the bosses), David's was never touched again.