It's very simple physics: if your vehicle is much larger than the vehicle you crash into, you're going to have lower acceleration forces inside your vehicle and thus experience fewer injuries.
Sucks to be the person in the other vehicle though. The end result is an arms race of vehicle sizes.
That's a defeatist attitude. Most people I know have never been in a car accident (I actually have; I just remembered. I hit a bike when turning right when I just had my license; never happened since, fortunately. Nobody was hurt). But I live in a country that cares about safe traffic design; that matters a lot.
First, think of the stupidest guy you can think of and understand half of humanity is stupider than him.
Second, think of simply how many people and cars are on the road at any given time. Counting would be a fool's errand, to say the least.
Third, understand that driving a car is not something that comes naturally or instinctively. Some might be more talented drivers than others, but we all have to learn how to drive a car to varying degrees of competency.
Fourth and finally: Murphy's Law.
When you combine all of these together, it's a miracle that we aren't seeing several orders of magnitudes more car accidents on a daily basis. The old saying that you're more likely to be in a car accident going to the airport than the chance you'll be in a plane accident is based in reality.
If you get through life without being in a car accident, I reiterate you were a lucky bastard and I would sincerely be happy for your good fortune.
Live in Germany, driving for 25 years. Never was in an accident. Same as my father, who has been driving for more than 45 years. Anecdotes, I know, but I definitely know less people that were in accidents than those that were not.
Nobody in my wider family drives. But I remember 4 accidents. 2 as passengers in a car, which is already very rare in a family without cars. 2 hit by cars breaking traffic law when cycling. Nothing overly dramatic happened, but still.
Most of my relatives and friends have been in car accidents. 2 friends of friends even deadly.
Sucks to be the person in the other vehicle though. The end result is an arms race of vehicle sizes.