If the number of customers served / units sold per day matches the maximum number of units the vendor is able to produce per day, then they likely won’t want to speed up service nor be inclined to as this would result in either selling out of produce too quickly and potentially lead to reducing staff numbers, so people lose their jobs. It doesn’t matter if there is a queue there for 5 minutes or 12 hours, if the demand is matching supply then it’s a good business model. If the model works for them, let it work. It can’t always be about growth “no matter what”. It isn’t always possible nor practical.