Competition is one reason. Increased sales volume is a second. Social pressure is a third. It's why we get clean tap water for less money than it would cost som

Competition is one reason. Increased sales volume is a second. Social pressure is a third. It's why we get clean tap water for less money than it would cost someone to bring it by bucket. It's why a gallon of gasoline costs less than the bale of hay equivalent. Regardless of the mechanism, the world is full of examples of technology lowering costs. Certainly you're correct that not all of the cost savings will be passed on to consumers, but as long as the market is not a zero-price-elasticity monopoly immune to social pressure and government regulation, some savings ought to be passed on.