No, they're not trying to buy cars that kill pedestrians, they're trying to buy cars which are bigger than other cars, which they believe won't get them killed

No, they're not trying to buy cars that kill pedestrians, they're trying to buy cars which are bigger than other cars, which they believe won't get them killed in a wreck. So it's an arms race. The danger to pedestrians is just a side effect which isn't considered by the purchasers.