how did that happened?

first of all, we don't know what models of the two involved cars.

You can't make a judgement without doing case study.
That Acura lost control and ht the Volvo from the opposite direction with it's passenger side. That's SIDE IMPACT crash!, or T-bone accident. The 2 sides are the weakness of any car.

According to the IIHS's test, the Acura got all good rating, but still resulted 1 dead and 1 injury. What if they were driving a Neon or Yaris? maybe both dead... badly.

Well, Acura's 5-star rating is still not perfect, but that's one of the better cars on the market today.

If you still think it's useless to drive a better car, then good luck.