That true but i think most tourist stay in the tourist areas because well Brazil is still a 3rd World Country and it can be dangerous especially if you can't speak Portuguese. There were alot of tourist that were killed because there GPS made the wrong turn into the favelas.
Tourists rarely get killed in Brazil... and especially in the favela. The trafficantes don't allow that type of shit in their favela because it brings too much heat. Naw man.. the only dangerous areas are really in Zona Norte. You can go right up to Barra (and Barra is really safe).. it's just that most people are so content with the tourist areas that they never care about venture out.