Rotten tomatoes

Here is something I’ve noticed recently in light of the salmonella problems with tomatoes:

Many restaurants and fast food chains are temporarily not serving tomatoes to keep their consumers safe. Nice of them. But they haven’t altered the price of the food to reflect the lack of tomatoes. This may not seem like a big deal, but go to one of these places and ask for extra cheese and they’ll charge you $0.35 – 0.50. So why can they get away with charging extra for cheese, but not cutting the price of their tomato-containing food items that lack tomatoes? And why are people willing to pay the same amount for a burger that lacks a tomato as they would for one that had one?