Being in a car or aeroplane is totally different from playing a game, VR or otherwise. The motion sickness is a result of a mismatch between the sense of your own motion from what you are seeing, and the sense of your own motion from your inner-ear (which is basically an accelerometer).
In a car or an aeroplane, as long as you are looking at the window then there is no problem. (But often people get car-sick if they try to read a book or something, because then they can’t see the motion - they can only feel it.) But in a game, you can see the motion but not feel it - so that can also give motion sickness.
Many modern first-person games have an option for ‘mouse smoothing’ (or something similar), and that generally help reduce or eliminate motion sickness.