Wise as you may be, I'll stick to statistics. 25 People a day are killed in Sao Paulo every day compared to 3 or so in NYC.
How many are kidnapped in Brazil or any SA country for that matter per day? It's a common practice to kidnap and expect ransom in those countries.
Let's assess risk then, shall we? Of those killed, or kidnapped, of a population in the millions, your chances are extremely slight? Right? Wrong. Anyone who can post on FR would qualify as top tier in Brazil. I.E. The 1% upper crust VS the 99% everyone else.
My family hosted 3 exchange students from Brazil and over the past 30 years, we know them and their families very well. When members of our family go there, our friends assign guards and a driver to accompany them anywhere. Some 15 years ago, the guards had a shootout with attempted kidnappers on the street. No one harmed, but it put an exclamation point on the risk.
If you feel Brazil is safe, more power to you. Everyone else should be alert, aware and have lots of other folks around to discourage misdeeds.