But then AR's going to have a similar motion problem when you're up close to synthetic imagery instead of only having a little bit of it as an overlay.
I always get a headache when using an iPad in the backseat of a car. But not in a train. I always wondered why this was, because it doesnt happen with my phone and never used to happen with my gameboy as a kid. Is this the phenomena you are referring to?
Don't forget, people get nausea and vertigo in everyday life in certain circumstances - driving while reading for example.