But here's a quote from a pizza restaurant trade publication, PMQ, telling us how sneaky the practice has become, and the mindset entailed (entire article, which focuses more on servers helping themselves and giving friends free beer, here):
It’s also important to know how many servings you should get from a keg. For example, most owners know there are 1,984 ounces in a 15.5-gallon domestic keg, and they know they pour 16-ounce pints, so they assume 124 servings per keg. However, with the evolution of the 14-ounce pint glass (in combination with ½” head), they should expect closer to 155 servings per keg. At $4 per serving, that adds up to $124 per keg in lost revenue! Determining how much you’re actually pouring is a vital step to reducing shrinkage.Is that wrong? Well, if the beer is priced accordingly--i.e. if they're giving you 14 ounces of Sierra Nevada Bigfoot for $3.50--nothing's wrong with that at all. But if they're pricing a "draft pint" to be 33% more than the price of the same beer in a bottle, then it's time to call foul, and let them know why.
More commentary here. Also more on the topic from Oregon.
It does take guts to walk into a bar, order a beer, and then pour the contents into a measuring beaker. You run the risk of being banned from some places, I'm sure. But I have done it.
(Tip o' the hat to Tom Cizauskas)