Auggie:

Wisconsin also (in the same statute) specifies in elegant detail how margarine must be packaged when sold at retail. It is also illegal to place margarine on the table at any public eating establishment unless specifically requested by the customer.

These regulations stem from a huge battle in the state's Legislature during the middle sixties (before it was legal to even possess margarine in the state). The "dairy defenders" who violently opposed the attack on the state's primary agricultural industry dreamed up all manner of reasons why the "synthetic" substitute for pure, wholesome butter should not be allowed to invade America's Dairyland. It would cause all manner of ailments, it would dull young children's senses to the point of distraction in school, it would devastate the agricultural economy; . . . take your pick.

As an interesting aside, after this battle was decided (resulting in the passage of the statute you cite to), one of the prime advocates for butter, a Senator from the Southern Wisconsin hill country, began a similarly passionate opposition to the trend toward open display and sale of contraceptives in pharmacies. Heretofore, such items were available only behind the counter. The Senator famously argued (and this is on the state's legislative record) that if these things are made more widely available, the poor people will start to use them and we won't have enough young men to meet the needs of our military draft.   -    Remember, this was during the VietNam War era.