Still no explanation why it’s so much steeper in the Kosher/frum world. The LinkedIn thread above (posted by yuneeq) has a ton of competent commenters and no real explanations.
The biggest cost right now is transportation. In the non-kosher world, there are many local options to help keep the costs down. Walmart, Costco, Sam's Club, and others have been pushing "local grown" as if it's a "save the earth" change of heart, when in reality, it's just too cost prohibitive to ship produce from across the country. Kosher food (dairy, poultry, beef) is only made in very specific places, and local alternatives just aren't available, so we have to eat every freight increase or go without.