<p>This paper argues that the bystander effect in rescue situations emerges to a significant extent from structural constraints preventing some willing rescuers from acting, rather than from insufficient altruism or traditional coordination failure. When multiple individuals intend to help but only one can act effectively, structural constraints necessarily frustrate some altruistic intentions, creating an observational equivalence problem: non-rescue may reflect either genuine indifference or frustrated willingness that courts cannot distinguish. I analyze why this behavioral indiscrimination is legally relevant. To do so, the paper extends the volunteer’s dilemma to prove that structural constraints generate endogenous inequality in agency even among ex-ante symmetric players and produce welfare losses that transfers cannot eliminate. The framework reconciles the empirical ubiquity of rescue with robust bystander effects, addresses gaps in Levmore’s information aggregation approach and modern accident law economics, and generates new implications for duty-to-rescue laws. It is shown that optimal legal rules must distinguish preference-based from constraint-based non-action and show that cross-jurisdictional variation between civil-law and common-law approaches reflects differences in structural constraint severity.</p>