If you've ever seen a TrailBlazer or other lagre SUV rollover or actually hit something bigger than itself, you'd realize this firsthand. Many of these vehicles, especially in a rollover, have poor sturctural support and the roof can, and does, collapse crushing the occupants. No side curtain airbag or crumple zone will protect the front-seat passengers when the A-pillars collapse and allow the roof to come down on them.