We’re talking about the built in navigation and passenger access while moving.
This is a "tricky" one. How car system would know that it is a passenger and not the driver who attempts to use navigation screen?
If, for example, manufacturer will "invent" an additional button on the steering wheel that, let's say, would be marked as "Passenger access allowed"

- what are the chances that driver would not use it for him/her self?
Of course, manufacturer can link passenger seat airbag sensor to navigation control but what about when it is not a passenger in the seat but a heavy bag?
Next step - add cameras in each corner of the cabin - just in case if rear seat passenger also want to do some adjustments to the navigation screen - then camera AI will "allow" such move.
It is all doable - no doubts...at some point in the future we, most likely, would be riding in driverless cars and at that point - we will be allowed to do whatever we want...would we?