I attribute it to a wealth of active and passive safety innovations. Surprised that the article didn't mention these. Much better crumple zones, electronic stability systems, ABS, curtain airbags, sturdier pillar support in rollovers, etc. Even as recently as the 1990s, many vehicles were death traps on wheels. Electronic stability and dual airbags were considered "optional" or "luxury" items back then, and they were non-existent most domestic and Japanese vehicles. You were lucky to just get 1 driver-side airbag. Nowadays multiple airbags and stability sensors are standard items on even basic run-of-the-mill vehicles.