The main concern of restaurant and cafe security is not the crimes but more of hygiene control in the food handling department. Some kitchens are not being watched over and thus if a health related outbreak occured, there is no telling where it originated from. As far as crime related situations go, most often than not is an internal crime such as when cashiers decide to steal some money from the register or give their friend free meals.
CCTV surveillance cameras are able to detect these situations and even much more when you integrate with video analytics. This way, you are able to analyze customer behaviour for business intelligence and at the same time judge employee's productivity.
If theft were to occur and if dispute were to take place, or even any harassment by unruly customers, surveillance cameras provide additional proof and evidence for the authorities.