The American chocolate thing isn't about chocolate %. An American came up with a process to help preserve the dairy, however this creates an amount of butyric acid as a bi-product. Completely fine health wise, but the only time a normal person would otherwise encounter butyric acid is when vomiting. Its largely responsible for the iconic taste and smell associated with vomit. So for people that didn't grow up eating American chocolate, American chocolate literally tastes like vomit.