I had the same questions and found this article:
https://snacksafely.com/2016/06/kelloggs-unintended-conseque...Basically, there were stricter measures put in place called HARPC. From my linked article:
> The new directives mandate that the “Top 8 allergens” identified by FALCPA (peanuts, tree nuts, milk, eggs, wheat, soy, fish, and crustacean shellfish) must either be ingredients of the product and identified as such, or the manufacturer must take extra care (and cost) to ensure that there is no cross-contact with them. There is no middle ground or “out” for the manufacturer, which is why we believe “May contain” type label advisories are heading for extinction. And that poses a problem, at least in the short term.
> companies, when faced with the added burden of instituting and documenting cross-contact prevention measures as dictated by HARPC, may instead choose to add trace amounts of the allergen to the product, as doing so makes the allergen an ingredient of the product and obviates the need for preventative cross-contact measures for that allergen.
> it means that manufacturers will either take stricter measures to prevent cross-contact or add a trace amount of the allergen and list it in the ingredient list, thus eliminating the ambiguity that currently plagues us all.
> A compromise that might have avoided the unintended consequences of companies like Kellogg’s adding traces of allergens to their products is to have offered them a third option: A mandatory “May contain” label advisory for any product made on shared equipment or in shared facilities that did not meet the FSMA threshold for cross-contact prevention. Such label advisories are voluntary today, rendering them ambiguous at best, but a definitively worded and located advisory statement included on all such products would have provided a way for manufacturers to meet the requirements of HARPC without resorting to the addition of allergens.
So I'd be surprised if it was happening on an ongoing basis, but I can definitely see why people would be irked.