Here we go with another "science" lesson ... LOL ... That's simple dude ... they have survived because the car crumpled and absorbed all the shock ... that in turn reduces the rate of deceleration of the person in the car ... It's not the speed that kills you ... it's the sudden stop at the end ... If you come to an instant stop , your brain , liver and other internal organs keep on going and mulch up in your cranial cavity , chest cavity or abdomen ... so the victim can look totally unscathed but be as dead as a door knocker ... Both positive AND negative G-forces can be a bad thing ...
Driving a big strong heavy vehicle is NOT always safer ... fools in 4WD's get killed in relatively minor roll overs because sitting up high above the vehicles centre of gravity is the same as being strapped to a chair on top of a ladder ... if the ladder gets pushed over , the person sitting in the chair slams into the ground with far greater force than if they were in the same chair getting pushed over on the ground ... The people in the 4WD get their head smashed in on the pillars , each others head , windows or ground due to the rapid acceleration during a roll whereas the person in a sports car will have a bruised elbow , shoulder or a lump on their head ...
Stronger is not always better ... to test that out ... get dropped from a cliff in an air filled rubber bladder ... then try the same stunt feeling safe and secure inside a 1 foot thick walled steel barrel ... LOL ...