Let's say you're a student in class. There are boxes full of delicious snacks on a table in front of the room: muffins, peanut brittle, candy, samosas (deep-fried potatoes wrapped in a packet of dough). There's a money box next to the snacks.
It's up to you whether to pay or not. And nobody's watching.
Would you be an honest citizen and toss some coins into the box? Or would you walk off with a snack without chipping in?
That's the premise of the honesty shop – an unattended business that relies on the customer to do the right thing.