"Do you think it's because they're living in poverty and privation and reacting to the many pressures that result from such conditions?"

Difficult question without actually reviewing some comparative anthropological type study about different culture's prevailing attitudes to women and to sexual violence. Anything else can only be mere supposition - however interesting that might be to those doing the supposing ;-)

I for one don't necessarily buy that poverty and associated 'pressures' causes a culture to normalise sexual violence against women.