The environment in Vietnam is hazardous no matter how careful you are. The environment at Nova is hazardous if you are lazy. That is the difference. B is blaming Nova for his laziness. He doesn't want to accept responsibility himself for something which is bad. Classic attribution theory.
If you are cautious in Vietnam, you can avoid the problems which many soldiers have. The lazy soldiers will sustain injuries.
Whatever. This isn't interesting for me anymore.
I am not going to be convinced that Nova is responsible.
I think the point I needed to emphasize (sorry for dragging this on) is that out of 15 teachers about 5 have bad backs. I think statistics determine if people have reasonable control over the situation or not.
Basically, I agree that one-off injuries are usually the individuals fault due to laziness etc, but when the numbers are larger (like in very hazardous environment, like Vietnam) the environment is to blame. The unresolved issue (for me) is where exactly on that scale does the `Nova back injuries` issue lie.