I don't think the trick would work without the line around the wallet. It makes the object look surreal, as though it has been put there for some unknown purpose. People walking past suspect that both they and the wallet might be being observed, so they don't touch it. The context and appearance of the wallet are too odd for people to be able to process the information that they have about it.
The aim of this trick of the mind is to make people feel so weird about picking up the wallet that they would rather play safe and not touch it.See how it works