Abstract This paper studies the political determinants of inequalities in government interventions under majoritarian (MAJ) and proportional representation (PR) systems. We propose a probabilistic voting model of electoral competition with highly targetable government interventions and heterogeneous localities. We uncover a novel relative electoral sensitivity effect that affects government interventions only under MAJ systems. This effect tends to reduce inequality in government interventions under MAJ systems when districts are composed of sufficiently homogeneous localities. This effect goes against the conventional wisdom that MAJ systems are necessarily more conducive to inequality than PR systems. We illustrate the empirical relevance of our results with numerical simulations on possible reforms of the US Electoral College.