I find that hard to believe, especially in places that serve alcohol. $12 for a glass of wine when you could buy a bottle for that price in a store. $8 for a shot of Jack Daniels? A whole bottle cost around $12 in a store, and how many shots are in a bottle? 20? Thats $160 they are getting for a $14 bottle (which they probably paid even less than that since they probably get a bulk discount).
A half barrel keg of Budweiser (yes I know its shitty beer) runs $100 and contains 1984 ounces. They sell 16 ounce draft beers for $5 each. Thats 124 glasses of beer which means they are raking in $624 for a $100 keg (also assuming they aren't getting a bulk discount)
Soda is a money grab too. A 5 gallon bag of syrup makes 30 gallons (3840 ounces) of soda and the average soda is 20 ounces so they get 192 glasses from a bag of syrup and most places charge about $2.50 (on the low end) for a soda, which means on a $93 bag of coke syrup (currently at Sams Club), they are making $480.
And dont even try to tell me those $5 orders of fries cost any more than 40 cents or so. Fresh potatoes are about $5 for a 10 pound bag at a grocery store, and most restaurants are paying a lot less per ound when they buy 500 pounds at a time