Since the study was authored by brazilians who only used data from brazil, it's hard to tell if the fatalities were enabled by the brazilian electrical system and would not happen elsewhere. Especially given that 4/5 were in rural areas.
Also, rural household wiring is often dogshit all around the world with many places having bad earthing.
Look around on the Internet and you'll definitely see how a lot of electrical systems in Brazil are not quite up to North American standards. Grounding is part of it.