This paper develops the idea that observer equivariance—the invariance of physical description under changes of observer perspective—provides the origin of symmetry in physics. Rather than assuming symmetry as a primitive principle, it is argued that it can be recovered from the structural requirement that different observer perspectives yield equivalent descriptions. The argument is formulated within a categorical and principal-bundle setting, where observer perspectives form the fibers and structural content forms the base. On this basis, standard symmetry principles appear as consequences of inter-perspective equivalence rather than postulates. The approach clarifies the role of invariants, the relation between measurement and law, and the conceptual link between symmetry and experience. It suggests that physical law emerges from the structural constraints required for a shared and consistent world among observers.