Libertarians: this is why we have building codes. We don't need builders cutting corners and harming people years down the road, because profit convinced them that was the right thing to do for their own interests.
I'm not pointing this out to blame those people in any way, but it may be legitimately they can't afford better housing and this is the best they could do and the risk of dying in an earthquake was better than their alternatives. Maybe sturdier housing everywhere would mean some those people would have been dead long ago from exposure.