You're not wearing your eyeglasses in chain restaurants.
To find out how strongly nutritional information affects purchase decisions (if at all), researchers interviewed New York City restaurant patrons in 2007 and 2009—one year before and then nine months after the city required fast-food joints to post calorie counts. The researchers, who published their findings in the British Medical Journal, found that the labels failed to stop patrons in their tracks: Only about one in six lunchtime customers said they noticed or read them. However, these people (usually women, unsurprisingly) placed orders that had about 106 fewer calories, on average, than the others. The researchers don't know exactly how these people scaled back their orders (did they order smaller fries? skip the cheese? or did they go for grilled instead of fried?), but they did conclude that the labels had an overall positive effect. Seek out the charts, skim the info, and then ask yourself if the tortilla is worth the extra calories (290, if you're wondering).