What you said is surely true but taking precaution can help us avoid the worse while driving. Moreover, we tend to neglect these basic things
The truth is that nothing is ever 100% preventable. A failed injector or blown head gasket could cause oil or antifreeze leaks. You could leave the parking lot full of air pressure and than run over a nail and blow out your steer tires. A pretrip wont prevent any of these things.I have had all of them happen to me after a thorough pretrip.The only way to handle emergencies out of your control is to stay calm and accept the current situation and what you can do to resolve it. That is all you can really do.This is a power that I completely lack at the moment due to my anxiety disorder which is why I am currently not driving at this time.