I think (hope) they mean as a passenger. The various bumps and turns are likelier to throw off your aim on a virtual keyboard compared to a proper tactile keyboard.

heh, No as a passenger. but I will say if a car has a touchscreen as a primary control device. not only are those miserable to use while driving, they should probably not be used while driving for the same reason you don't want to be using your phone while driving. if you are lucky it will have large fixed predictable (virtual)buttons. however even then it usually requires visually fixing your hand to the keyboard and there is no way to touch it without activating it. this is what makes it miserable to use in a vehicle. what would help(a little, not much) is a big bar to rest your hand on. See also: why touch controls are terrible in a vehicle.