It's not the slant so much as the width - it wouldn't be thick enough, close enough, and leave such poor visibility were it thinner. But it's required to be thi

It's not the slant so much as the width - it wouldn't be thick enough, close enough, and leave such poor visibility were it thinner. But it's required to be thicker to survive a rollover without the big heavy body crushing the roof (and occupants). I've driven vehicles that don't have to survive a rollover (a few models of New Flyer diesel bus). The A pillar being slanted or straight makes no difference. It's the thickness that'll block a pedestrian.