When refrigeration engineers design supermarkets, they tend to use reach-in glass door cabinets for low-temperature display cases. Although this makes shopping a little inconvenient for customers, these cases are less problematic than open display cases.
Open display cases at low temperatures are more sensitive to the store's environment. Their evaporator coils tend to freeze up more quickly, requiring longer and more frequent defrosting. Because of this, reach-in glass door freezers are more often chosen to display frozen food products since they are more reliable and less troublesome at low temperatures.