The "supervised by parents" rule is about the same in Wisconsin, except that there's evidently no pre-defined age minimum.
The drinking age is still 21, but only because the federal government threatened to take away highway funding if Wisconsin refused to raise the minimum.
Then again, over 40% of Wisconsinites claim German ancestry.
(disclosure: I live in Wisconsin and have German ancestry. And don't particularly like beer, aside from a strawberry-rhubarb seasonal one. But I also don't drink to get drunk.)