It always seemed like a logic gate thing to me, like the Fullmetal Alchemist rule of equivalent exchange. Otherwise, there comes a point where there would be no order or structure to the universe and the benefit is boiled down to simply preserving reality.
Basic supply and demand economics. When supply is high and demand is low, prices fall. When demand is high and supply is low, prices rise. They think people will willingly sit in line regardless of the price because, in reality, people have.
Conversely, they wouldn’t want to drive people away when business is slow and can easily jump into another drive thru.