Similar debate happened in India for Milk products especially sweets when they introduced GST. Milk has no GST, 5 % on dairy Product but if products made of condensed milk then it is 18%.

It is so silly and feels like no brainier to imposes same tax for all products of same kind but when policy makers are seeing from 10000 feet high, small things like status of tomato is not visible to them. Someone should tell them "The devil is in the details".