The problem isn't paying for an extra shot. The problem is paying for a second shot. See, if I get a normal size coffee I am happy with one shot. If I am getting a large coffee, I expect a double shot, as I am paying for a larger size anyway. Why should I pay for that extra shot on top of the larger size coffee. The consistency is gone if I get a large coffee with a single shot. I am paying for a large coffee, but it is weak due to one shot. It would be like if I paid for premium petrol, and it was watered down, but for me to get the right consistency, I am paying extra on top of the premium price. That extra shot doesn't cost the seller $4, so you aren't losing $4. If you were to charge an extra $1 per shot, you are losing that potential dollar. You could also lose customers through this. That is the trade off. If I go into a coffee shop, I don't know what to order as there is no standard or consistency. It isn't that I don't know what I am talking about, it is just that I am unfamiliar with this shop. I normally ask what will be a decent strength, but not be overly strong and go from there. I can appreciate paying extra if someone wants an extra shot that wouldn't be needed to maintain consistency and for less used items such as decaf, soy, etc., but if I had to pay extra for full cream or an extra shot needed for a consistent strength and I am already paying extra for the next size up, you will lose me as a customer and many more people.