Overpouring happens everywhere alcohol is served. Every ounce poured into a drink and not charged for means revenue is lost. That extra ounce poured could have been upcharged for a double, or could have been poured into a second drink.
If overpouring results in lost revenue, then underpouring would result in extra revenue right? WRONG
There is no easier way to lose regular customers or discourage new customers from returning than underpouring drinks.
Pouring each drink consistently benefits owners, managers, bartenders, and guests; while overpouring or underpouring rarely benefit any of them. Owners receive revenue from ALL their inventory, managers deliver a consistent customer experience, bartenders receive bigger tips from higher tabs, and guests will return and refer the venue to others.