No problem with it working for alcohol. If a parent is found supplying underage minors or their own kids with alcoholic beverages they are busted. Obviously it occurs when you allow your 16 year old to throw a party and the cops are called for all the noise. If the kids are standing around holding a beer that adult parent is leaving in cuffs.
That may vary by State. Here it is technically legal for a parent to take their kid to a bar and buy them alcohol. Although I have never witnessed this occurring. It is also legal for a 21yr old husband/wife to buy alcohol for his/her 18-20yr old spouse in a bar as well. I have seen that done. In fact I knew a girl that at 21 that got her 19 yr old brother into a bar once claiming they were married since they had the same last name and address. Lucky for them the door man didn't make them kiss to prove it. I know the brother would have ralphed on the spot at just the thought. I have heard of some bars that require seeing the actual marriage certificate to do this though.