Slip and fall cases involving self serve restaurants and other businesses are required to ensure that customers do not create dangerous conditions for other customers. This is arguably a high standard because it means that employees of a business should regularly check the premises to see if a customer left something on the floor that someone could slip on or some other hazard like that. In these types of businesses, employees may have to take extra steps to ensure the safety of customers because some members of the public can be especially careless and pose a danger to other customers.
This differs from other types of businesses that are not self serve because in those cases it can be very difficult to prove that the business is at fault for something that another customer did. In those cases it is much easier to prove fault when an employee has created a dangerous condition.
So if you were injured in a self service type restaurant like a buffet or other self service type business it is good to keep in mind that it may be easier to prove the business was at fault as long as you can show the employees were not taking the proper precautions to keep the business safe.