People suck and will take advantage of whatever they see fit.

Back when I was in college, I worked in the cafeteria of one of the residence halls. The cafeteria was an all you can eat buffet style establishment. On more than occasion, I had to bust people for stealing food. The popular method if you were a female was to put a gallon zip lock bag in your purse, get your food, deposit food into the gallon bag/purse, wash, rinse and repeat.