&gt;Now that you mention it, I can&#x27;t help but wonder why Starbucks doesn&#x27;t have to &quot;prove&quot; that its 12oz latte really is 12oz. Is it because I have the right to immediately measure it and complain?<p>In a different life, I worked at Starbucks. About once a quarter (per my recollection) we got secret shoppers who, among other things, would actually weigh the drinks they ordered to ensure employees were making them correctly. Bad reports were a pretty big deal, so management tended to take care to respond to any problems quickly.<p>And yes, you could absolutely complain if you ordered a 12 oz latte and received one that was only 3&#x2F;4 filled. You&#x27;d get it remade immediately and probably a coupon for a free drink on your next visit (at least, that was policy at the store I worked at, when I worked there).<p>Things like scales (for weighing purchased coffee beans, as well as internal use) were actually certified by the county department of weights and measures every year.