It’s the other way around. Low places are higher income in favelas and barrios because they’re closer to public transportation, formal services, commerces and salaried jobs. The higher you are in a favela the poorer you are and the worse are the living conditions. For the lack of vehicular access and the chaotic nature of improvised construction means government institutions have a harder time reaching people there. So there’s no service support, fewer commerce, lack of legal protection and you’re so far away from the formal city that job opportunities are meager.