I should amend my statement that supply and demand theory is a lie, pure myth, faith-based. I think the traditional representation of supply and demand curves may apply under certain circumstances that represent a relatively narrow slice of the entire economy. Mainstream economists try to apply the supply and demand curves too widely, and draw wildly dystopian conclusions that say more about them than about a money-creation-funded basic income.

Why aren't any case studies of supply and demand easily available? The theory is presented as true without needing any support, except in vague general examples that could also be explained by other theories. Are their any empirical examinations of how supply-and-demand theory predictions are correct?

My guess: supply and demand theory is a social truth, the acceptance and promulgation of which helps you "fit in". Economics has adopted supply and demand theory out of tradition, respect for elders, and cognitively captures people by extending social support to those who publically espouse it.