Actually centilitres of alcohol per measure would be a more accurate method, assuming that people actually measure their drinks in mls, etc. Units have often been seen as arbitary - one glass of wine has many a meaning
I do get confused with units per measure, and it's annoying that it's a 'voluntary' thing for companies to announce their calories/units on their products. ... So I think it's a good thing. If young people are more aware of what is in their drinks, and how drunk they are likely to get (not that many care! lol) - they may think twice.
I am always also quite surprised at the amount of people - quite innocently - not knowing how many units they've consumed to legally still be allowed to drive. The information is out there, but that's the thing. You need to go and find it - and not many people take the initiative to do so. If it's stamped clearly, on the bottle, it makes no excuse for errors! ... not that I would ever touch a drop of alcohol if I was driving - but many people do.