Judge Allows Lawsuits to Continue
Here is a link to a story about the class-action lawsuit about underfilling drinks, and here is a link about the lawsuit accusing Starbucks of using too much ice in their iced drinks.
While I am no longer a fan of Starbucks (weakened rewards program, too little Fair-Trade coffee, too much resource impact with energy usage and landfill waste, far too much sugar in their food, and more) - I personally feel that they do not underfill drinks. It makes no sense for the to do that, and anger people. Also they are good at listening to custom orders so for example if someone wants less foam, you just have to ask.
For Latte's, they use the full shots of espresso so underfilling would mean what? Too little milk? If that were consistently done, then the drinks would taste too strong - but you don't hear people saying that.
The foam in a Latte or Cappuccino will settle if you don't drink it right away. To some that might appear to be underfilling, but it is just settling - and will happen with such drinks from any vendor.