Fact, not joking around. Apparently, the U. S. A. never really got over Prohibition. While the Bureau of Alcohol, Firearms, and Tobacco set standards for alcohol, all 50 states have their own ideas about how to enforce those standards. Here in California, alcohol is illegal for anyone under 21 to consume, purchase, or possess. Anyone supplying alcohol to a minor can be held liable under the law. But we're far from being the most stringent. Some states will not allow the public to purchase alcohol for consumption off the premises except in state-run liquor stores. Others allow 18-year-olds to drink wine or beer, depending on the alcohol content. Other states allow ale and beer, only with fairly low alcohol content. Thus 4.2% "beer" or "ale."
I could go on and on, but this is why there is so much variation. It's also why many good brews are only available in their own states: many smaller breweries simply can't afford to bottle/can (or brew!) 14 or 15 different alcohol contents for sale outside their state. (The big guys like Anheuser-Busch and Guinness are big enough and wealthy enough to handle it.)
Since Elf Ale is whatever you prefer, and will never make you fail a breathalyzer test, I never worry about it!