Apple provide the API, so this is just the car manufacturer doing "the right thing".

I think the wording may some "certain cars" enforce it because after-market head units may not be connected up to the speedometer and therefore have no way of including this information.

We have a Suzuki that’s supposed to disable most of the touch screen controls when driving (including the TV/DVD and changing any navigation settings aside from zoom), but the used car dealer we bought it from informed us that he had already disconnected that sensor as a routine service to us...

I assume the car companies asked for this functionality. Mazda's UI locks out a bunch of functionality when the car is in motion.