Four-way stops are exercises in decorum without supervision! Every driver knows the rules about who goes next and who has the right of way should turns be involved. There is no traffic light or police officer to ride herd over the proper behavior. And, at four way stops drivers are more careful and courteous than they might be with yellow traffic lights.
Customers love to be trusted. The newspaper machine trusts you will take only one paper when you could take the entire stack to share with your friends. The open air market assumes no one will shoplift an apple. Are there ill-mannered thieves who greedily hoist their way onto the system? Of course. But, the typical customer who is trusted responds by refusing to game the system.
Trust begins with an attitude toward customers. Signage, for instance, communicates a lot about your attitude toward customers. “No Smoking” can easily become “Thank you for not smoking” and with greater success. “Overdue Fees” at the library sounds much harsher than “Extended Use fees” like the movie rental store. What signs of trust can your customers see in how you serve them?