Real world such as seeing approaching trains or being in one isn't a problem - the sickness manifests only when the "seen reality" doesn't match "felt reality", i.e., when a display tries to fake reality. Reading in a car might be similar, yes - if you are feeling the movement change but you are so engrossed that your eyes tell that you don't seem to be moving. Games and movies would cause problems only if they're "too immersive" - small screens and unrealistic graphics wouldn't cause it, but a 3d screen all around you would.

My (completely unverified) opinion is that there is a solid evolutionary basis for this - I mean, if your vestibular system gives different movement perception than your visual system, then that usually (in older times 100% ?) is a common symptom of poisoning, probably caused by some psychoactive substance in something you ate, and vomiting is an appropriate built-in reaction to try to mitigate that poisoning.