exactly. social phenomena in general are many orders more complex than physical phenomena for which mathematical models are generally deployed effectively.

but even so, a zero- (e.g., a single tax rate) or quasi-first-order (like a limited number of tax brackets) model makes no sense, when we can much better fit the desired effect with a slightly higher-order function for only a small complexity trade-off. better fit means reducing the exploitation surface.

tangentially, this is a relevant application of basic linear algebra and calculus to civics, which could be used as concrete motivation in the high school education of those subjects.