The No-Meat-Buffet Restaurant is a vegan restaurant that offers vegetarian dishes and soy-based protein entrees. Diners are given cafeteria trays and plates for their trips through the buffet line.

There is a fixed price for the buffet for which a customer is entitled to a single trip through the buffet line. Return trips through the buffet line are not allowed unless the customers pay again. Customers have the option to purchase a beverage at an additional cost. Customers who purchase beverages are given plastic glasses. Those who do not purchase beverages are given paper cups for water.

Barb Strauss, the buffet owner, has noticed that profits have been falling even though the customer count has been steady. After examining food costs, she has focused on the beverage service, where costs have risen.

Barb asked Carol Garland, the assistant manager, what she thinks might have caused an increase in beverage costs. Carol feels the problem lies in people taking beverages for which they have not paid. She has seen it many times.

In Barb's mind, taking a beverage without paying for it is stealing. Carol agrees, but she doesn't know how it can be prevented. There aren't enough employees to watch the beverage service constantly. When staff members see a paper cup used for another beverage they politely remind the customer that there is an extra charge for a beverage. Barb wants a better way to detect beverage theft.

What do you think is the optimal role for detection in this situation?