I just took a cpr class and statistically, if you find someone post adolescent in trouble, it is due to a heart attack. Even cpr is not a miracle action, it only helps to prolong your life. 6 minutes without oxygen is all it takes until you are (brain) dead. And 6 minutes is not that long at all. If you can get to shore and someone can administer cpr on you (within 6 minutes) than those 6 minutes are extended until professional help arrives. But who can get to shore in 6 minutes? And what if you lose consciousness in those 6 minutes?
Cpr does 2 things: 1) puts some fresh oxygen in your lungs 2) Helps your failed heart circulate oxygen to your brain. If your brain doesn't get oxygen in 6 minutes, life is over.
I think it would be great if every one who drove a car knew cpr. It is just a little something to help extend someone's 6 minutes before death. I agree that life is safer in pairs.