Here’s what Iearned from reading Cook’s Illustrated.
Brands of kosher salt are different. Ordinary table salt weighs 10 oz. per cup; Morton’s Coarse Kosher Salt weighs 7.7 oz. per cup; and Diamond Crystal Kosher Salt weighs 5 oz. per cup. Keep this in mind. If a recipe calls for kosher salt and the amount seems unusually large, the recipe may have been tested with a coarser salt such as Diamond.
The New York Times informed me that the salty chocolate chip cookies had been tested with Diamond Kosher, which is much less salty than Morton kosher. This explains why the cookies were so salty.