Polygamy is accepted in South AFrica.

https://en.wikipedia.org/wiki/Polygamy_in_South_Africa#:~:

So I'm going to disagree with you on that. Monagamy is not necessarily the moral option.

I think violence against women is often driven by frustration and despair in other areas - poverty, lack of social status in the community, etc. Women just tend to be closer to home and weaker.