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Once upon a time, food production was largely cottage industries. The local dairyman brought milk to town. The local farmer brought chickens. The local gardener brought rutabagas. It was thus very easy to keep a kosher home. People knew the producers personally, and therefore knew the product.
As the techniques for mass production developed after the industrial age, kashrut had to take on new dimensions. Thus developed the concept of the hekhsher, kosher supervision. Rabbis would go out and put their seal on a product. We now see these marks on all manner of food. Some foods have a long history (comparatively). For example, Maxwell House coffee has been certified kosher since the 1920's. Coca Cola has been certified since the 1930's. Other products are more recent, such as M&M's and Oreos.
When we get to the Pesach time of year, the issues of supervision become a little more complex. We have to deal with the extra foods that are otherwise permitted, but forbidden during the holiday of Pesach. Within those foods, there is a category called kitniyot, which Sephardim eat but Ashkenazim do not.
In theory, this should be simple. It gets complicated though, because custom was never monolithic. It was subject to much interpretation depending on location, rabbi, product availability, and a whole bunch of other factors. It is thus impossible to say that Ashkenazim did 'X,' and Sephardim did 'Y.'
Now here is the issue. Some of those other issues have started to appear in ways that demand a new look at how products are supervised. For example, I cannot eat wheat or dairy. Other people are vegetarians. The list of quirks in people's diets is quite astounding.
Kashrut should be administered with those quirks in mind. If kashrut organizations do not wish to put all of the relevant information on the package, or if companies do not want to put all of the relevant information on the package, that is understandable. It gets crowded. It can still be put on the company websites. Oreos are certified as dairy, even though there is not a drop of milk in them. Okay, but for someone who has anaphylactic reactions to dairy, it is nice to know that they should be safe. The certification as dairy alone is not helpful.
Kashrut supervision at present takes only the kosher diet into consideration. It needs to expand its mindset beyond, so that those who keep kosher can do so while also tending to individual dietary needs.
May the best of the evening be yours.