In the big chains it's overwhelming consolidation and cost cutting that completely eliminated flavor. Sugar and heat compensate for the lack of flavor. Finally, overweight and obese people perceive the things they eat differently than if their BMI was normal (personal experience going from obese class 1 to normal). If the majority of your clientele are obese or overweight, you will update the menu to appease their palate. Forty-one percent of U.S. adults, on average over the past five years, from 2017 to 2021, have characterized themselves as overweight or obese.
