It depends, the outcome can be the same.
A well run restaurant usually has 'trends", for example a family style restaurant may have lobster tail on the menu but they know exactly how many lobster talils they need to sell to see a profit and usually know how many to order each night.
Now the problem with the dining plan was that disney was only compensating restaurants a dollar amount for each ts credit. Lets say for the sake of argument it was 25 bucks. So even though the lobster tail may have cost the restuarant 50 dollars an order, disney was only giving up 25 ( I don't know the exact dollar amount, I'm just using 25 as an example.).
So lets say Yachtsmans steakhouse knows, hey on Friday night dinner we normally get 4 orders for lobster tails. Ok so if every one of those 4 orders is on the
ddp, we'll lose 100 bucks on this night, no problem that's acceptable but now because folks are no longer ordering normally and everyone is ordering lobster tails to maximize their credits. Now instead of 4 lobster tails going out, Yachtsman may get 15 orders. whoa baby now what we are losing is a problem.
So most places have a few choices, they can as Granny said raised prices but in today's environment folks don't like to see prices go up, that's why when you go to a supermarket, a manufacture will make a package smaller before they raise the price. Our brains naturally rebel against paying more, they can try to make up the difference in other ways i.e. charge for water, cut staffing, use cheaper ingrediants or they can do what disney did and dumb down the menu.
I think what my main comment is that for a restaurantaur, every aspect of your business effects your bottom line.
My family would have never, ever thought to say some thing to a customer who chose to bring in crystal light for their water
BUT if we saw customer, after customer, after customer doing it we would have definitely reacessed and figured out what that was doing to the bottom line. It's not only what they are doing that affects us but it's also what they are not doing (purchasing beverages) that affects the bottom line.