I saw this at MOMA this past January and as I see it is up on video now I thought I'd summarize.
The period in question is the nasty Isabel Peron dictatorship and the equally nasty dictatorship that replaced it. Disappearing people had been occurring in Latin America for hundreds of years and this period was no different. That is one of the underlying themes, and one of the few scenes that worked is a scene of local people going to a home and emptying it of anything of any value. It reminded me of a scene in Kazantzakis' Zorba where the moment the ageing widow dies, all of the town turns up to calmly steal everything not nailed down. The film also has some brief moments of great cinematography.
It also is clearly influenced by Fargo, True Detective and some aspects of Scandinavian noir, although wihtout the depth, dark humor, or coherence.
Ultimately though. Rojo. is entirely incoherent. it not only fails to tell a meaningful story, it fails to tell an intelligible one. it is a tedious experience to watch it, with no reward at all for the audience.